KABUL (Reuters) - Taliban insurgents killed 10 French soldiers and wounded 21 in a major battle in Afghanistan, the French president’s office said on Tuesday, the biggest single loss of foreign troops in combat there since 2001.

Bodies of suicide bombers are seen after they detonated themselves in Khost province, eastern Afghanistan, August 19, 2008. REUTERS/Stringer

The Taliban have gradually closed in on Kabul in the past year, making travel south, west or east of the capital extremely hazardous for troops, aid workers and civilians and spreading fear among the population.

French President Nicolas Sarkozy is to travel to Afghanistan on Tuesday in response to the attack, his office said.

“My determination is intact. France is determined to continue the struggle against terrorism for democracy and freedom. The cause is just,” Sarkozy said in the statement.

The French soldiers were killed in a major battle that erupted when Taliban fighters ambushed their reconnaissance patrol from three sides in mountainous country in the Sarobi district, about 60 km (40 miles) east of Kabul on Monday.

Nine were killed immediately when the lead section of the patrol dismounted from their vehicles at around 1:30 p.m. (0900 GMT) to reconnoiter on foot. A 10th died later when the vehicle he was in overturned.

The battle that ensued lasted deep into the night and the mixed French, Afghan and U.S. force summoned reinforcements and air support, General Jean-Louis Georgelin, chief of the army general staff, told a news conference in Paris.

A “large number” of insurgents were killed in the fighting, NATO’s International Security Assistance Force (ISAF) said.

France has 2,600 troops in Afghanistan, after Sarkozy sent an extra 700 soldiers this year in response to a U.S. call for NATO allies to provide more forces to check a surge in violence.

The deaths brought to 24 the number of French troops killed in Afghanistan since U.S.-led and Afghan forces ousted the Taliban in 2001 for refusing to give up al Qaeda leaders behind the September 11 attacks.

The 10 dead and 21 wounded soldiers were from the 8th Marine Infantry Parachute Regiment, the 2nd Foreign Parachute Regiment and the Regiment de marche du Tchad, a mechanized marine unit.

The Afghan Defence Ministry said 27 insurgents were killed or wounded in the fighting and at least two Afghan soldiers were wounded.

The Taliban Web site said 20 U.S. soldiers had been killed in the fighting, which they said started after militants ambushed a convoy of Afghan and foreign forces late on Monday. The insurgents commonly refer to all foreign troops as American.

TALIBAN CLOSING IN

The Taliban have stepped up attacks in provinces bordering the Afghan capital over the past year, closing in from the volatile south and east, where the bulk of the fighting has occurred since militants relaunched their insurgency in 2005.

“What we’ve noticed in recent operations is a greater capacity from the Taliban to organize and maneuver and as we saw in this incident, they don’t seem to have any problems securing ammunition,” Georgelin said.

Kabul has had fewer suicide bombings so far this year compared to 2007, but the attacks have been far more daring and have hit higher-profile targets, increasing the sense of insecurity in the capital.

While fighting raged east of Kabul, a wave of Taliban suicide bombers and gunmen attempted to attack the main U.S. base in southeastern Afghanistan. They were repelled by ground troops and attack helicopters, NATO-led forces said.

ISAF troops killed seven of the insurgents, six of them suicide bombers, after they spotted them preparing to attack about 1,000 meters (yards) from the base.

Soldiers opened fire with small arms, then “helicopters arrived on station soon after and engaged these insurgents as they attempted to flee from the scene”, ISAF said in a statement. “Three of the insurgents killed themselves by detonating their suicide vests. ISAF forces killed three other suicide bombers before they could detonate their vests. There were no ISAF casualties in the attack,” it said.

A suicide car bomber rammed the gates of the same base, close to the border with Pakistan, on Monday, killing 10 Afghan civilians and wounding 13 more.

Camp Salerno is a large, sprawling base with a runway and helicopter landing pads close to the town of Khost and is the main hub for mostly U.S. troops in southeastern Afghanistan.

More foreign troops have been killed in Afghanistan in the past three months than in Iraq where the United States has twice as many soldiers than all the international forces fighting the Taliban.