KABUL – U.S.-backed Afghan forces have killed at least 33 militants in three days of fighting against suspected Taliban insurgents in southeastern Afghanistan, the U.S. military said on Saturday as Afghan officials reported 20 more deaths.

Afghan and U.S.-led coalition forces have been engaged in a major operation against suspected Taliban and al-Qaeda bases in the mountains of Daychopan district of Zabul province, 300 kilometres (190 miles) southwest of Kabul.

U.S. military spokesman Colonel Rodney Davis said the coalition confirmed at least 33 militants were killed in fighting between Monday and Wednesday.

Afghan officials in Zabul said a further 20 suspected Taliban were killed on Friday while U.S. aircraft were Saturday continuing to bomb suspected militant bases.

"At least 20 Taliban were killed yesterday in Daychopan district of Zabul province and two government soldiers were slightly injured," said Haji Sadow, secretary for Zabul security commander Haji Ayob.

Zabul governor Hafizullah Hashim also told AFP that up to 20 militants were killed in eight hours of fighting on Friday.

"Their bodies are scattered in the area. They (the Taliban) have been weakened and I think they cannot pose any threat to us any more," Hashim said.

Sadow said fighting was continuing Saturday in the mountains as U.S. aircraft bombed militant bases.

"The Taliban are surrounded by government forces in the mountains of Daychopan. American aircraft are bombing their bases in the mountains," Sadow told AFP by satellite phone.

"The fighting is still going on. Since Daychopan is a mountainous area so it is hard to locate enemy positions and they can easily change their positions and hide, but the operation is going on successfully and area will be cleaned up very soon," he said.

Colonel Davis confirmed that anti-extremists operations were continuing but would not provide any further details, citing security reasons. Davis was not able to confirm the Afghan officials' claims of 20 killed on Friday.

One U.S. Special Operations soldier died Friday morning of injuries sustained in an accidental fall during a night combat assault near Daychopan, the U.S. military said.

A U.S.-led coalition soldier was also wounded during a firefight near Daychopan Thursday night. The soldier, whose nationality was not disclosed, was airlifted to a U.S. military hospital in Germany.

Southeastern Afghanistan has been hard-hit by an apparent resurgence of Taliban fighters.

President Hamid Karzai said militants had attacked a checkpoint in the southern border town of Spin Boldak Friday night, but there were no casualties. He was addressing a ceremony Saturday marking the inauguration of the new Afghan National Army's central corps.

Afghan authorities believe up to 300 Taliban were regrouping in mountains in Zabul and neighboring Uruzgan, the birthplace of the Taliban's fugitive spiritual leader Mullah Mohammad Omar.

The 12,500-strong U.S.-led coalition force is currently hunting al-Qaeda and Taliban remnants, mainly along the 2,400-kilometre (1,500-mile) Afghan-Pakistan border.