KABUL- Taliban insurgents on Monday launched a grenade and gun attack on Kabul airport, firing on military facilities before being overwhelmed in an operation hailed as a victory for Afghan security forces.

Two suicide bombers blew themselves up and all five other attackers were killed when elite Afghan troops stormed two multi-storey buildings where the militants were holed up near the airport's perimeter fence.

The security forces' response was widely praised as a sign of their growing professionalism as they take over responsibility from 100,000 US-led combat troops who will pull out by the end of next year.

President Hamid Karzai, who is currently visiting Qatar, highlighted the effectiveness of the foreign-trained units after only two civilians suffered minor injuries in the attack. "Brave Afghan security forces have the ability to repel any enemy attack and can protect people and their country," Karzai said in a statement.

Loud explosions from rocket-propelled grenades (RPGs) and sporadic bursts of small-arms fire erupted for about four hours after the fighting awoke residents of the Afghan capital at 4:30 am (midnight GMT). "There were seven assailants - two (suicide bombers) died detonating themselves and five others were killed," Kabul police chief Mohammad Ayoub Salangi told reporters.

The heavily-guarded airport, which has both civilian and military terminals, contains a large base for the US-led NATO coalition deployed to help Afghan forces thwart the 12-year insurgency. "We can report that RPGs were fired in the direction of the airport but we don't have any news of damage," a NATO spokesman told AFP.

Three suicide vests were found in the buildings where the insurgents had used RPGs and machine guns to fend off Afghan forces and to attack the airport on the northeast side of Kabul. The militants, who wore military and police uniform, did not manage to breach the airport grounds, though all flights were cancelled or re-routed for several hours. A Taliban spokesman said the group was responsible for the attack, adding that a large number of foreign and Afghan soldiers had been killed - a claim dismissed by Afghanistan and NATO. A car laden with explosives at the scene was detonated deliberately by police using a RPG, a senior official said.

The ability of Afghan police and soldiers to suppress the Taliban insurgency is crucial to the government's efforts to avoid spiralling instability as NATO combat troops withdraw.

Meanwhile, Afghan authorities on Monday accused Taliban militants of beheading two children for spying, but insurgency leaders denied the gruesome charges.

The boys, aged 10 and 16, were beheaded on Sunday in the southern province of Kandahar after they collected left-over food from a police post, provincial police spokesman Ghorzang Afridi told AFP.

"The children used to go to a police checkpoint to collect food and other things thrown away by police, so the Taliban thought they were spies and abducted them and beheaded them," Afridi said.

"They were poor children who lived on collecting scraps and leftovers," he added, saying that villagers found the two boys' bodies in a remote area of Zhari district and informed police.

Kandahar provincial spokesman Javid Faisal confirmed the incident, but the Taliban denied any role in the children's deaths.

Speaking to AFP from an undisclosed location, Taliban spokesman Qari Yousuf Ahmadi dismissed the allegations as government propaganda and condemned the murders.

"The government does this to distract from attacks such as in Kabul this morning," Ahmadi said, referring to a Taliban strike on the capital's airport earlier on Monday.