Nasiruddin Haqqani, senior commander in powerful Pakistan militant group, shot to death, sources say

LONDON Nasiruddin Haqqani, the brother of the powerful Pakistani Islamic militant group's leader who also functioned as a senior commander and fundraiser for the Haqqani network, was fatally shot Monday in Islamabad, sources in the Taliban and in Pakistani intelligence told CBS News.

The Haqqani network has been one of the most lethal forces battling U.S. troops and their allies in neighboring Afghanistan, and Nasiruddin's death represents a significant blow to the organization.

His demise came not as the result of a U.S. drone strike -- as have many other recent militant leaders' -- but rather at the hands of gunmen who killed him from their vantage point on a motorcycle, according to Pakistani intelligence sources.

The sources told CBS News Islamabad bureau chief Maria Usman that Haqqani was gunned down outside a bakery in the northeast Islamabad neighborhood of Bhara Kahu.

The assailants fled the scene, and there was no immediate claim of responsibility for the shooting.

A source in one of Pakistan's other powerful Islamic extremist organizations, the TTP, or Pakistani Taliban, told CBS News' Sami Yousafzai on Monday that was friction between the two groups.

The source said TTP (Tehreek-e-Taliban) leader Hakimullah Mehsud, who was killed in a Nov. 1 U.S. missile strike in Pakistan's volatile North Waziristan region, had angrily referred to the Haqqani brothers as "puppets" of the country's intelligence agency just before his death.

A former minister in Afghanistan's Taliban government, which was toppled in the 2001 U.S. military invasion following the Sept. 11 terror attacks on New York and Washington, told CBS News that the slain Haqqani was the group's representative to the Quetta Shura -- the Afghan Taliban's pseudo administration-in-exile, based in the sprawling southern Pakistani city of the same name.

"He was the main fundraiser of the Haqqani network in Gulf states, and had warm relations with al Qaeda and foreign fighters," the former Taliban minister told Yousafzai, on the condition he not be further identified.