Taliban insurgents killed 10 Afghan troops in an ambush in western Herat province, police and government officials said Tuesday.

A spokesman for the provincial governor, Muhiudin Noori, said the Afghan troops — which included both soldiers and police — were searching late Monday for a group of insurgents who had earlier set up a roadblock, stopping and seizing passing vehicles, when they were ambushed.

Five policemen, including the district commander and five soldiers died in the ensuing firefight, Noori said. There were no insurgent casualties, but police later arrested 25 suspects found in the area, he said.

Also Tuesday, an American service member was killed in an insurgent attack in the east, the U.S. military said in a statement. It did not provide further details about the attack. The latest death makes at least 12 American service members killed so far this month and 265 killed so far this year.

The Herat ambush was the bloodiest single incident for Afghan security forces this year in western Afghanistan — an area where the insurgents have been less active than in their strongholds in the east and west of the country.

In recent months, Taliban guerrillas have been switching tactics and increasingly targeting Afghan security forces as the international coalition continues its drawdown toward a planned withdrawal of the majority of combat troops in 2014.

Meanwhile, President Hamid Karzai condemned "in the strongest possible terms" a NATO raid on Sunday in Logar province in which he said four children were killed.

A presidential statement said coalition troops carried out the operation in Baraki Barak district in an effort to apprehend two armed militants. But this resulted in the deaths of the four children who were tending to their animals in the same area, it said.

Din Mohammad Darwesh, spokesman for the provincial governor, said the victims were between 10 and 13 years old.

NATO on Tuesday acknowledged that its forces "may be responsible for the unintended, but nonetheless tragic, death of three Afghan civilians" during the operation in Baraki Barak district. Coalition commander U.S. Gen. John R. Allen expressed his condolences to the families of those killed.

There was no immediate explanation for the discrepancy in the number of victims in the two statements.

In recent months, Karzai has criticized the international military coalition for what he said was the killing of civilians in Afghanistan, for not going after terrorist safe havens in neighboring Pakistan and for not providing the Afghan forces with all the weapons they need.

The criticisms drew an angry response from U.S. Defense Secretary Leon Panetta, who earlier this month said the Afghan leader should occasionally say "thank you" to allied forces who are fighting and dying in Afghanistan, rather than criticizing them.


Associated Press writer Slobodan Lekic in Kabul contributed to this report.