The US military says it has evidence that elements within Pakistan's military intelligence agency, the ISI, continue to provide support to the Taliban.

Officials said that this support for militants had to end. The chairman of the US Joint Chiefs of Staff said the ISI had links with militants on both Pakistan's borders with Afghanistan and India.

Two senior figures within the US military have spoken about the links they believe exist between elements in Pakistan's Directorate for Inter-Services Intelligence (ISI) and Taliban and al-Qaeda militants.

"There are certainly indications that's the case," said admiral Mike Mullen, chairman of the Joint Chiefs of Staff, in a CNN interview. "Fundamentally, that's one of the things that has to change."

In another interview, head of the US Central Command general David Pet­raeus said some of the militant groups had been established by the ISI and that their links continued. He added there was evidence that "in the fairly recent past" the ISI had tipped off militants when their positions were in danger.

American officials, speaking anonymously to The New York Times, have given more detail.

They said the strengthening Taliban campaign in southern Afghanistan was being made possible by military supplies from Pakistan.

The newspaper said electronic surveillance and informants had shown the level of co-operation was deeper and more extensive than earlier thought.

Pakistani leaders have publically denied any links with the militants.

The US military's assertion follows the recent announcement by US president Barack Obama about a new strategy for the "increasingly perilous" situation in Afghanistan. He said an extra 4,000 US personnel would train and bolster the Afghan army and police, and he would also provide support for civilian development.

Afghan president Hamid Karzai said he was "in full agreement" with the US review.