Efforts by NATO-led forces to recover the remains of a troop-carrying helicopter that crashed during a fight with the Taliban have been hampered by attacks in nearby areas.

By Sunday evening, Afghan and American forces were engaged in clashes with fighters in the Tangi Joy Zarin area of Wardak province's Sayd Abad district where the US Army Chinook helicopter was destroyed late on Friday, killing 30 US troops and eight Afghans.

"There have been a small number of limited engagements in the same district as yesterday's helicopter crash, however, those clashes have not been in the direct vicinity of the crash site,'' NATO said in a statement.

"As of now, we have no reporting to indicate any coalition casualties resulting from these engagements.''

Wardak provincial spokesman Shahidullah Shahid confirmed to The Associated Press news agency that the  recovery mission was still under way despite the threats of more violence.

"A clearing operation is ongoing in the district and there are reports of casualties among insurgents,'' Shahid said. "The area is still surrounded by American forces.''

Elsewhere in Afghanistan, NATO said four alliance service members were killed on Sunday in two separate attacks in the east and the south. The deaths bring to 369 the number of coalition troops killed this year in Afghanistan and 46 this month, according to reports.

Taliban claims attack

More than 20 US navy SEALs from the unit that killed Osama bin Laden were among those killed in the helicopter crash, though none of the victims were involved in that raid.

The troops from SEAL Team Six were flown by a crew of the 160th Special Operations Aviation Regiment, according to one current and one former US official. Both spoke on condition of anonymity because families are still being notified.

One source said the team was thought to include 22 SEALs, three air force air controllers, seven Afghan army troops, a dog and his handler, and a civilian interpreter, plus the helicopter crew.

The Taliban quickly claimed to have shot down the helicopter during a firefight. They also said eight of their fighters were killed in the fighting.

"They wanted to attack our mujahideen who were in a house, but our mujahideen resisted and destroyed a helicopter with a RPG [rocket-propelled grenade] rocket," Taliban spokesman Zabihullah Mujahid said by telephone.

Sources on the ground told Al Jazeera "the helicopter was apparently taking off from a roof of a building during this operation when it then crashed".

Al Jazeera's correspondent in Kabul, Bernard Smith, added: "It is looking like it is going to be one of the single largest losses of life for coalition forces in Afghanistan in the last 10 years."

Investigation under way

NATO said on Sunday that it was probing the Taliban's claim of responsibility and investigating the crash site of the aircraft, a twin-rotor Chinook helicopter.

Aircraft crashes are relatively frequent in Afghanistan, where insecurity and difficult terrain make air travel essential for coalition forces transporting troops and equipment.

In June 2005, 16 US troops were killed when their helicopter crashed in eastern Kunar province after apparently being hit by a rocket-propelled grenade.

There have been at least 17 coalition and Afghan aircraft crashes in Afghanistan this year.