KABUL, August 6, 2008 (AFP) - A US Marine deployed in Afghanistan to fight Taliban extremists was killed by a bomb while five policemen and several rebels died in new clashes, US and Afghan officials said Wednesday.

The Marine was badly wounded when the explosion hit a military patrol in the western province of Farah on Monday, the US-led coalition said.

Three other soldiers were hurt in the blast, which was similar to hundreds carried out by insurgents from the Taliban, in government between 1996 and 2001, or other radical outfits.

Such explosions have killed seven US soldiers this month, with 152 international soldiers losing their lives in Afghanistan this year, mostly in attacks.

A major battle erupted Wednesday in Farah -- an opium-producing province on the border with Iran -- when Afghan security forces escorting a convoy to a military base were ambushed, a police unit commander said.

In several hours of fighting, five policemen were killed and three wounded, said Sayyed Farid Bakhtawar.

He said 10 of the attackers had also died, although the government did not have their bodies as proof.

The coalition announced meanwhile that there had also been heavy fighting about 50 kilometres (30 miles) northeast of Kabul in the province of Kapisa.

'Several militants were killed and two were detained Tuesday during a Coalition forces' operation to disrupt militant activities in Kapisa province,' it said in a statement.

Insurgent-linked unrest has risen sharply over summer with major clashes and deadly Taliban attacks.

Afghan and US officials have also said there are more non-Afghan militants in the country, most said to arrive via sanctuaries in Pakistan, which is under pressure to take firmer action against extremism.