US Defence Secretary Robert Gates on Thursday said Pakistan's failure to put pressure on Taliban forces on the country's border with Afghanistan had fuelled a rise in violence, but said Islamabad appeared to recognise the problem.
A 40 percent spike in violence in east Afghanistan in the first five months of 2008 "is a matter of concern, of real concern, and I think that one of the reasons that we're seeing the increase ... is more people coming across the border from the frontier area," Gates told a news conference.
He said "the ability of the Taliban and other insurgents to cross that border and not being under any pressure from the Pakistani side of the border is clearly a concern."
Gates said the issue "needs to be addressed with the Pakistani government" that came to power after February 18 elections won by parties opposed to US ally President Pervez Musharraf.
He said cross-border infiltration and violence had increased in the past few months after peace deals were negotiated with Taliban elements and other militants.
"What has happened is that as various agreements have been negotiated or were in the process of negotiation with various groups by the Pakistani government, there was the opportunity -- the pressure was taken off of these people and these groups.
"And they've therefore been more free to be able to cross the border and create problems for us."
But he said he was encouraged by the response from Islamabad to the problem, citing a statement by the prime minister that the government plans to "reassert its control and authority in the northwest frontier province."
"The fact that the Pakistani government itself has recognised that this is a problem and that these groups' activities are a problem for the Pakistani government as well as for those of us in Afghanistan, I think is a heartening sign."
He added: "And my hope is that the prime minister's statement today indicates a willingness to reassert that pressure."
Gates spoke amid growing unease in Washington and Kabul over Pakistan's efforts to broker deals with Taliban militants, which President George W. Bush's administration fears could give the insurgents a chance to regroup.
Pakistan has denied charges from US and Afghan officials that it is turning a blind eye to Taliban and al-Qaeda forces based in restive tribal zones, saying it faces a porous border and that security forces have had bloody clashes with militants.
Relations between the United States and Islamabad have been strained since a US air raid in Pakistan on June 11. Washington said it was targeting militants but Pakistan said 11 of its soldiers were killed.