Under a deal the Taliban signed with the United States in February, the insurgents agreed to stop Al-Qaeda from using Afghanistan as a safe haven to plot attacks.

But in the months since, the Taliban have continued to work with Al-Qaeda in the Indian Subcontinent (AQIS), the US Defense Department said in a report.

"AQIS routinely supports and works with low-level Taliban members in its efforts to undermine the Afghan government, and maintains an enduring interest in attacking US forces and Western targets in the region," the Pentagon said in a security assessment compiled for the US Congress.

"Despite recent progress in the peace process, AQIS maintains close ties to the Taliban in Afghanistan, likely for protection and training."

The Pentagon report comes on the heels of a UN analysis released last month that found Al-Qaeda and the Taliban "remain close" and were in regular consultations over negotiations with America.

Afghan watchers have long questioned whether Washington is being naive in thinking the Taliban would honor a pledge to restrict Al-Qaeda, the jihadist group behind the September 11, 2001 attacks that led to America's invasion of Afghanistan.

The report added that any "core" Al-Qaeda members still in Afghanistan are focused mainly on survival, and have delegated regional leadership to AQIS.

"AQIS's interest in attacking US forces and other Western targets in Afghanistan and the region persists, but continuing coalition (counterterrorism) pressure has reduced AQIS's ability to conduct operations in Afghanistan without the support of the Taliban," the Pentagon said.

The UN report highlighted the connections between Al-Qaeda and the Taliban, who sheltered former leader Osama bin Laden in Afghanistan ahead of 9/11.

The two groups "remain close, based on friendship, a history of shared struggle, ideological sympathy and intermarriage," the UN report stated.

The US-Taliban deal signed February 29 was supposed to lead to peace talks starting by March 10 between the insurgents and the Kabul government.

But negotiations have proved elusive amid a contentious prisoner swap and rising violence.

Under the US-Taliban deal, foreign forces are supposed to quit Afghanistan next year.

But General Kenneth McKenzie, who heads US Central Command, said last month that "conditions would have to be met that satisfy us -- that attacks against our homeland are not going to be generated from Afghanistan" before the US would pull out.