Washington's special representative for Pakistan and Afghanistan has said the US must put more pressure on Islamabad to aid efforts against the Taleban.

华盛顿巴基斯坦和阿富汗问题特使表明，美国必须对伊斯兰堡施加更多压力并帮助其对付塔利班。

Mr Holbrooke said America's vital interests were at stake in the region

Richard Holbrooke said the US could not succeed in the Afghan conflict against the Taleban without Pakistan's support.

He was speaking on the eve of a meeting between US President Barack Obama with the leaders of the two countries.

It comes as Pakistani Taleban militants¹ appeared poised²（稳重的，泰然自若的） to end a truce³（休战） and the Afghan Taleban launched new attacks.

"We need to put the most heavy possible pressure on our friends in Pakistan to join us in the fight against the Taleban and its allies," Mr Holbrooke told a Congressional hearing in Washington.

He said America's most vital（至关重要的） national security interests were at stake in the region and that the US "cannot succeed in Afghanistan without Pakistan's support and involvement".

Mr Holbrooke cautioned against describing Pakistan as a failed state and reconfirmed US support for President Asif Ali Zardari, saying Washington's goal "must be unambiguously to support and help stabilize⁴ a democratic Pakistan headed by its elected president".

But he said Pakistan had to "demonstrate its commitment to rooting out al-Qaeda and the violent extremists within its borders".

The US believes that Taleban fighters are able to seek sanctuary⁵（避难） in Pakistan's border regions in order to launch attacks in Afghanistan.

The talks come at a time of increasing Taleban activity in the region

Growing unrest

Mr Zardari and his Afghan counterpart, Hamid Karzai are due to attend a three-way summit with Mr Obama on Wednesday.

Speaking at the Brookings Institute think tank in Washington DC, Mr Karzai said his country could never be stable or peaceful unless alleged⁶ Taleban sanctuaries⁷ and training grounds in Pakistan were removed.

He said Afghanistan would use the talks to do "all that it can in immense（巨大的，广大的） friendship and brotherhood⁸ with Pakistan and alliance and friendship with America" to address the issue.

Their talks come at a time of new unrest in both countries as a result of Taleban fighting.

Hundreds of residents of Pakistan's Swat Valley fled their homes on Tuesday as a peace deal between the army and the Taleban appeared close to collapse⁹.

Officials say up to 500,000 people are expected to flee and authorities are preparing six refugee camps for them.

There have been clashes between the army and militants in Swat and heavy battles in neighbouring districts.

A major army operation against the Taleban in Swat Valley does seem likely, the BBC's Syed Shoaib Hasan reports from Islamabad.

In Afghanistan, reports say more than 20 Afghan civilians¹⁰ were killed by US air strikes on Tuesday.

Fighting in Farah Province also reportedly killed 25 Taleban militants.

An Afghan official told the BBC he had seen more than 20 bodies, including women and children, lying in two lorries outside the governor's house.

The official said those who transported the bodies said they had been killed by American air strikes.

America's military said they were investigating the reports.

The issue of civilian¹¹ casualties is hugely sensitive in Afghanistan, the BBC's Martin Patience reports from Kabul.

President Karzai has repeatedly urged international forces to take greater steps to avoid them.