Separately, the Afghan government said it was checking reports by locals saying some 40 Afghan civilians were killed in a raid by foreign forces in Sangin district of southern Helmand province on Friday.

In Nuristan’s Barg-e Matal, dozens of Taleban fighters and up to six Afghan police were killed during days of clashes before the district fell to the Taleban overnight.

Barg-e Matal is important for the government and militants because of its location and has regularly changed hands.

Lying near the border with Pakistan, the rugged district has been used as a supply route for arms and fighters for the Taleban in three provinces, most importantly for Badakhshan where the Taleban have mounted a series of deadly attacks recently.

Afghan police forces withdrew from Barg-e Matal to avoid high casualties and in the face of sustained Taliban pressure after days of skirmishes, Interior Ministry spokesman Zemarai Bashary told reporters. “Right now the police forces in Nuristan are working to recapture it,” he said.

The Taleban have yet to comment about the fall of the district and the reported losses in their ranks.

In Helmand province, where the Taleban insurgency is strongest, Bashary said provincial authorities were checking reports by residents that dozens of civilians were killed in a raid by foreign forces on Friday.

Further details were not immediately available.

Meanwhile, the Taleban have offered to exchange the body of a US Navy sailor they said was killed in an ambush two days ago for insurgent prisoners, an Afghan official said Sunday.

US and NATO officials confirmed that two American Navy personnel went missing Friday in the eastern province of Logar, after an armored sports utility vehicle was seen driving into a Taleban-held area.

Taleban spokesman Zabiullah Mujahid said the pair drove into an area under insurgent control, prompting a brief gunfight in which one American was killed and the other was captured.

He said both were taken to a “safe area” and “are in the hands of the Taleban.”

Mujahid did not mention any offer to exchange the pair for Taleban prisoners. A local Afghan official said the Taleban sent a message through intermediaries offering to hand over the body in exchange for jailed insurgents.

Abdul Wali, the deputy head of the provincial governing council, said local authorities responded by saying, “Let’s talk about the one that is still alive.” The insurgents said they would have to talk to superiors before making any deal.

Hundreds of posters of the two missing sailors have been hung at checkpoints throughout Logar province where NATO troops are stopping vehicles, searching people, peering inside windows and searching trunks.

“Our latest, accurate information reports are that they are still in the area,” said Din Mohammed Darwesh, spokesman for the provincial governor of Logar.

He said the governor’s office was upset because the two Americans left their base without notifying Afghan security forces in Logar.

“This was an abnormal situation,” Darwesh said.

The visiting chairman of the U.S. Joint Chiefs of Staff, Adm. Mike Mullen, told reporters on Sunday that he didn’t have all the details, but “from what I know right now, this is an unusual circumstance.” Mullen said he could not comment on the Taleban claim that one American was killed and the other was captured. He says the US is doing all it can to “return to American hands anybody who has been captured or killed.”