KABUL, Afghanistan — U.S. Special Forces killed six Afghan police and wounded 13 early today in a case of mistaken identity by both sides after the police fired on the Americans during an operation against an insurgent commander, officials said.

A U.S. military statement said police fired on the American forces after the troops battled and killed an armed militant in the city of Qalat, the capital of the southern province of Zabul. The Americans returned fire on the police but only later learned their identities. One Afghan civilian was also killed in the exchange.

"Coalition forces deeply regret the incident of mistaken fire," said Col. Jerry O'Hara, a U.S. military spokesman. "Initial reports indicate this was a tragic case of mistaken identity on both parts."

Gulab Shah Alikhail, the province's deputy governor, said U.S. Special Forces carried out an operation in a small village near a police checkpoint on the outskirts of Qalat. The police, thinking it was a Taliban attack, opened fire, he said. Then a helicopter fired on the security post and destroyed it, he said.

LONDON — British troops will begin withdrawing from Iraq in March and will mostly be gone by June, the Ministry of Defense said today.Britain has about 4,000 troops in southern Iraq. It expects to begin withdrawing them after regional elections planned for next month, the ministry said, confirming reports in British media.The number of troops will fall to 300-400 by midyear, the reports said.A U.S. brigade will replace the British force at Basra airport, ministry officials told reporters from British media in a briefing Tuesday. The ministry confirmed reports of the briefing to The Associated Press.