U.S. expels Syrian envoy Zuheir Jabbour over Houla massacre along with other Western nations

Updated at 3:09 p.m. ET

(CBS/AP) WASHINGTON - The United States expelled Tuesday Syria's top envoy in Washington in response to a particularly gruesome massacre in which the United Nations says families, including children, were shot at close range in their homes, CBS Radio News correspondent Cami McCormick reports.

Zuheir Jabbour, Syria's charge d'affaires at the nation's embassy, has 72 hours to leave the country, State Department spokeswoman Victoria Nuland said in a statement. Syria has not had an ambassador in the United States since the previous envoy left last year to take another post.

"We hold the Syrian government responsible for this slaughter of innocent lives," said Nuland. "This massacre is the most unambiguous indictment to date of the Syrian government's flagrant violations of its U.N. Security Council obligations."

No action was taken against the handful of technical staff remaining at the Syrian Embassy, Nuland told reporters at an afternoon press conference.

The decision comes as governments around the world expelled ambassadors and top Syrian diplomats Tuesday in an unusually coordinated blow to Syria's leaders.

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Cranking up the pressure on increasingly isolated Syrian President Bashar Assad,

Britain, Canada, Australia, France, Germany, Italy, Spain, Bulgaria and the Netherlands also took action Tuesday against Syrian diplomats. Britain's foreign secretary said the countries involved in Tuesday's expulsions would also push for tougher sanctions against Syria.

The moves came after the killings Friday in Houla, a collection of farming villages in Syria's Homs province — one of the deadliest single events in a 15-month-old uprising against Assad that has killed thousands.

A U.N. report Tuesday said 49 children and 34 women were among the 108 people who died, but it did not decisively say who carried out most of the killings.

"We are at a tipping point," special envoy Kofi Annan told reporters Tuesday in Damascus, following a meeting with Assad. "The Syrian people do not want the future to be one of bloodshed and division."

He called on the government and the armed opposition to stop all violence. Later, Nuland, the State Department spokeswoman, said, "From our perspective, this has been tipping in the wrong direction for a long time."

According to the state-run news agency, SANA, Assad blamed terrorists and weapons smugglers for scuttling Annan's peace plan. The regime denies there is any popular will behind the country's uprising, saying foreign extremists and terrorists are driving the unrest.

The new information provided by the U.N. draws attention to the role of the shabiha in 15 months of violence in Syria. Assad's government often deploys pro-regime thugs or armed militias to repress protests or carry out more military-style attacks on opposition areas.

They frequently work closely with soldiers and security forces, but the regime never acknowledges their existence, allowing it to deny responsibility for their actions.

A Syrian official denied again on Tuesday any involvement.

"It is irrational that any party who wants to make Annan's mission a success would ever commit such a massacre," Deputy Foreign Minister Faisal Mekdad told reporters. He said Syria remained committed to Annan's plan and "had not committed a single violation."

Activists have posted videos of tanks and armored vehicles in the middle of cities, a violation of the plan, and U.N. observers said they found spent tank and artillery shells in Houla after the massacre there. Funeral videos also showed local rebels among the mourners — making it unlikely they carried out the killings.

Diplomats at the U.N., the European Union and the Arab League have been working since the Houla massacre to coordinate new action against Syria's government, French Foreign Ministry spokesman Bernard Valero said.

"This is the most effective way we've got of sending a message of revulsion of what has happened in Syria," Australian Foreign Minister Bob Carr said in Canberra in reference to the expulsions. In a statement, he called the Houla killings a "hideous and brutal crime" and said Australia would not engage with the Syrian government unless it abides by the U.N. cease-fire plan.

The expulsions up the pressure on Syrian allies such as Russia. Russian President Vladimir Putin is traveling to Germany and France this week and is likely to come under even greater criticism of his Syria-supportive stance.

"We have to continue our work with the Russians," British Foreign Secretary William Hague said. "We will continue to discuss this with Russia. Russia has particular leverage on the regime and therefore has a particular role in this crisis."

Hague said that the situation in Syria is more complicated than what international powers faced in Libya last year, when the United Nations approved intervention against dictator Muammar Qaddafi's regime.

Britain is expelling three Syrian diplomats to protest the Houla killings, among them Charge d'Affaires Ghassan Dalla — the country's top ranking diplomat in London.

In Canada, Foreign Minister John Baird said all Syrian diplomats and their families have five days to leave. Another Syrian diplomat expected in Canada will be refused entry.

In France, Syria's former colonial ruler, new President Francois Hollande showed that he is not backing down from his predecessor Nicolas Sarkozy's tough line on Syria.

Syrian Ambassador Lamia Shakkour was notified Tuesday that she is persona non grata, along with two other embassy officials, the French Foreign Ministry said. Hollande said Shakkour is being expelled but that the timing is complicated by her dual status as Syria's ambassador to Paris-based UNESCO.Hollande said that after high-level discussions with British Prime Minister David Cameron and Ban, it had been decided to deploy "a certain number of ... pressure tactics," against Syria.

Germany on Tuesday announced Syria's ambassador had three days to leave. Foreign Minister Guido Westerwelle said Germany and its allies hope "that this unambiguous message does not fall on deaf ears in Damascus."

"The Syrian regime bears responsibility for the terrible events in Houla," Westerwelle said in a statement. He said Germany will push for the U.N. Security Council to consider the situation in Syria again.

"It has been clear not just since Houla that Syria has no future under Assad," Westerwelle said.

The Italian Foreign Ministry said Syrian Ambassador Khaddour Hassan was ordered out of the country. Spain said it was giving Syrian Ambassador Hussam Edin Aala and four other diplomats based in Madrid three days to leave.

Australia gave Charge d'Affaires Jawdat Ali, the most senior Syrian diplomat in Australia, and another diplomat from the Syrian Embassy, three days to leave the country.

Bulgaria gave its Syrian diplomats three days to leave.

Other countries stopped short of expulsions, either to protect their ties with Damascus or because some Syrian ambassadors serve several countries simultaneously.

Dutch Foreign Minister Uri Rosenthal declared the Syrian ambassador to his country "persona non grata" but said he would not be expelled because he is also Syria's ambassador to Belgium. "It is no longer possible to work with a country with such a president," Rosenthal said on the ministry's official Twitter feed.

Sweden is not expelling Syrian diplomats because the Swedes are concerned that would affect their own diplomatic presence in Syria. Sweden believes that it's important to maintain that presence in order to have contacts "not least with the opposition," said Foreign Ministry spokeswoman Catarina Axelsson.

In Vienna, Foreign Ministry spokesman Nikolaus Lutterotti said the Syrian ambassador was being summoned to the ministry where officials will deliver a very hard protest about the massacre.

When asked if the expulsions were EU-wide, Lutterotti said this had not yet been decided. He said the ambassador to Austria would not be expelled as he holds an additional function as the representative to the U.N. organizations in Vienna.

Turkey said it has no immediate plans to expel anyone. Tunisia, the birthplace of Arab uprisings against entrenched autocrats that spread across the region last year to Syria, had already expelled Syria's ambassador.

There was no public Syrian reaction to the coordinated expulsions. Phone calls to Syria's embassy in Paris were not answered, and an official at the Syrian delegation to UNESCO refused to comment.

The U.N. estimates 9,000 people have been killed since the uprising began in March 2011. Assad's regime denies there is any popular will behind the country's uprising.

Hollande said Tuesday that Paris will host a meeting in early July of the so-called Friends of Syria seeking a diplomatic solution to the conflict.