The attack on Camp Salerno, 30 kilometres (19 miles) from the border with Pakistan, came as NATO's International Security Assistance Force was involved in heavy fighting near Kabul after French troops were ambushed Monday.

About 30 fighters tried to storm Salerno, the largest US base in eastern Afghanistan, Khost province governor Arsala Jamal told AFP.

They struck a day after a suicide car bomb outside the base on Monday killed 10 Afghan labourers waiting to enter and wounded 13 more.

In Tuesday's attack the rebels were stopped about 1,000 metres (yards) from the camp, ISAF said in a statement.

Troops in the base had identified them "posturing to attack the base and engaged them with small-arms fire," it said. Helicopters arrived soon afterwards and opened fire on the rebels as they tried to flee, it said.

Seven were killed, six of them suicide bombers, ISAF said. Of those, three died after they detonated their suicide vests and three other would-be suicide bombers were killed by troops, who suffered no casualties.

Afghan defence ministry spokesman General Mohammad Zahir Azimi said 13 attackers were killed.

"Six blew themselves up, six others died in the explosions and one died in gunfire from commandos. Their bodies have been recovered," Azimi said.

"A most intense terrorist mass suicide operation was thwarted," a defence ministry statement said.

It was the biggest attack on a US military base since fighters stormed an outpost in northeastern Kunar province in July 13 and killed nine US troops, wounding 15 more.

The Khost governor's office said two children had also been killed in the fighting. Some of the attackers had fled to nearby houses and corn fields and troops were searching for them, added the governor.

The insurgent Taliban movement claimed responsibility for the attack. "A group of 30 mujahedeen (holy fighters) armed with rifles and suicide jackets attacked the American base in Khost," spokesman Zabihullah Mujahed said.

The hardliners, who are linked to Al-Qaeda, also claimed responsibility for Monday's suicide attack. Soon after the deadly bombing, troops were able to prevent a second suicide blast.

French NATO troops were meanwhile involved in heavy fighting Tuesday with insurgents about 50 kilometres (30 miles) east of Kabul in Sarobi district, the alliance force and military officials said.

The fighting erupted after insurgents attacked a military patrol Monday, the ISAF media office said. "We had a fight through the night and it is ongoing," an ISAF officer told AFP on condition of anonymity.

An Afghan military official said there had been heavy casualties to both troops and rebels.

The Taliban were driven from power in a US-led invasion in late 2001 because they would not hand over their Al-Qaeda allies wanted for the September 11 attacks on the United States.

However, they regrouped, with some of them taking refuge in Pakistan, to launch a snowballing insurgency that military officials say is attracting more Arab, Pakistani and other Muslim fighters.

This year has seen some of the deadliest insurgent attacks, with violence said to be up 50 percent in some areas compared with 2007.

In other violence Tuesday, a bomb struck ISAF troops in the southern province of Kandahar, killing an Afghan interpreter, a district police chief said.

And 10 rebels were killed in fighting overnight in Helmand province, the defence ministry said.

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