The military said on Monday two US marines were killed as they were checking a cave pounded by warplanes in a five-hour battle in eastern Afghanistan.
Meanwhile, with rebels suffering heavy losses in a string of clashes, a veteran Afghan official said Taliban leader Mullah Omar might be ready to make peace - and that the government should welcome him.
The US military said Sunday's clash began when a unit of marines investigated a report in Laghman, about 100km east of the capital, Kabul.
Insurgents allegedly opened fire on the marines with small arms and rocket-propelled grenades and then split into two groups, one of which fled to a village and the other to a cave on a nearby ridge, according to a military statement.
"US Air Force A-10 aircraft engaged the insurgents in the cave and a squad of marines went in afterwards to assess the situation," the statement said.
US statistics put the military toll
at 143 since 2001
"The two marines were killed while clearing the cave area."
Their names were withheld pending notification of next of kin. "Two insurgents were confirmed killed and another 21 suspected dead," the military said.
There was no word on any wounded from either side.
Fighters opposed to the US-backed government of President Hamid Karzai have ramped up their three-year-old insurgency after the melt of the winter's snow, carrying out a string of attacks.
Sunday's deaths bring to 143 the number of American troops killed in and around Afghanistan since the start of Operation Enduring Freedom in 2001, according to US Defence Department statistics.
However, rebels are said to have suffered massive casualties when American warplanes caught them in large groups on open ground.
In the bloodiest fighting in nine months, US and Afghan forces including US warplanes clashed with bands of suspected insurgents in two southern provinces last week.
Sixty-four rebels, nine Afghan soldiers and an Afghan policeman were reported killed, while six US troops were among the wounded.
US commanders say they are grinding the insurgents down and persuading villagers in a belt of territory along the Pakistani border to stop sheltering them.
They also suggest that the 18,000-strong US-led force could be trimmed after 18 September parliamentary elections, if a government reconciliation plan takes off.
President Karzai and US officials have said the process should be open to all "non-criminal" Taliban and members of other groups.
Officials say several dozen former fighters have come forward and will be accepted back into Afghan life.
But the head of a peace commission supposed to oversee the process said on Monday that the offer covered even Taliban leader Mullah Muhammad Omar and former prime minister Gulbuddin Hekmatyar, both wanted by the US.
Even Mullah Omar is welcome to
rejoin life, an Afghan panel says
Sibghatullah Mujaddedi, a former Afghan president, said he would negotiate with any Afghans ready to lay down their arms and recognise Karzai and Afghanistan's new democratic constitution.
"Sometimes policies towards some people change, and this was the old policy toward Mullah Omar and Hekmatyar," Mujaddedi said at a news conference. "Our commission is independent and we want to deal with all individuals."
Mujaddedi said he had cleared his approach with the government, though officials in Karzai's office declined to comment.
Out of line
US spokesman Colonel James Yonts said the military was studying his remarks, but suggested he had stepped out of line.
"Our position all along has been that those guilty of serious crimes must be responsible for their actions," Yonts told The Associated Press. "We believe the government of Afghanistan understands and supports that."
Mujaddedi said the commission did not know where Omar and Hekmatyar were, but insisted the fighters were growing tired of "fleeing from cave to cave".
"If they come and join the peace process, we will see what their conditions are. If they are acceptable for us and the government, we will accept them"
former Afghan president
"From what we understand, these two individuals regret fighting and are not interested in fighting any more," Mujaddedi said.
"If they come and join the peace process, we will see what their conditions are. If they are acceptable for us and the government, we will accept them."
Separately, the US military said it had found no trace of a radio station which a purported Taliban spokesman claimed was broadcasting last month near the southern city
"To date, we don't have any actionable intelligence that this radio station exists," spokeswoman Lieutenant Cindy Moore said.