Many people have fled Swat to be in safer parts of Pakistan
The US has expressed concern over a deal Pakistani authorities reached with pro-Taleban militants in the Swat valley in north-western Pakistan.
The agreement allows the imposition of Sharia law in the region in return for an end to the Taleban insurgency.
Richard Holbrooke, US special envoy to Afghanistan and Pakistan, said he was worried it might "become a surrender".
The deal has been welcomed by many local people. But critics see it as a capitulation to the Taleban.
Mr Holbrooke, who returned this week from a tour of South Asia, told US network CNN he had discussed the issue in a telephone call with Pakistan's President Asif Ali Zardari.
He said Mr Zardari had assured him the deal was temporary and aimed at stabilising the troubled Swat region.
"It is hard to understand this deal in Swat," Mr Holbrooke said.
"I am concerned, and I know Secretary (of State Hillary) Clinton is, and the president is, that this deal, which is portrayed in the press as a truce, does not turn into a surrender.
"President Zardari has assured us it is not the case," he added, pointing out that the Pakistani president had described it as "an interim arrangement".
"He does not disagree that people who are running Swat now are murderers, thugs and militants and they pose a danger not only to Pakistan but to the US as well," Mr Holbrooke said.
Pakistan and Afghanistan are both sending high-level delegations to Washington next week.
"I can assure you, and President Zardari knows this, that this will be the top initial subject of conversation," Mr Holbrooke said.
Desire for peace
Talks on the deal have now started between cleric Sufi Mohammad, who signed the Sharia deal with the government, and the Taleban, who are led by his son-in-law, Maulana Fazlullah.
The Pakistani government has denied having made any "concession" to the extremists.
The BBC's M Ilyas Khan says it is unclear how much power Sufi Mohammad has as he has been away from the region for a long time.
Our correspondent says the cleric's repeated denunciation of armed violence has had little effect on militants, who draw influence from several groups of foreigners and militants from other areas of Pakistan who have infiltrated Swat.
But there is considerable war fatigue in Swat, and people would be happy to live under any system provided there is peace, he adds.
Tens of thousands of people have fled the former tourist haven.
More than 1,000 civilians have died in shelling by the army or from beheadings sanctioned by the Taleban.
The Taleban have also destroyed hundreds of schools in their campaign against female education.