KABUL: An Afghan soldier shot dead two Nato troops on Thursday as violent anti-US protests over the burning of copies of the Koran swept the country for a third day.

French, Norwegian and US bases were also attacked by protesters at rallies killing three people, taking the two-day toll to 12, officials said.

The attacks came after the Taliban urged Afghans to kill foreign troops to avenge the burning of Korans at a US-run base, although the militia stopped short of cutting off contacts with American officials in Qatar over the crisis.

Afghanistan is a deeply religious country where slights against Islam have frequently provoked violent protests, and many Afghans are incensed at the discovery of charred Korans at the US-run Bagram airbase north of Kabul.

Nato's US-led International Security Assistance Force (ISAF) said two of its service members were killed in eastern Afghanistan by “an individual wearing an Afghan National Army uniform” who turned his weapon against the troops.

ISAF did not identify the nationalities of the victims and gave no further details.

Asked whether the shooting was connected to anti-American protests, an ISAF spokesman said, “There was a demonstration in the province.”

Afghan troops defending a foreign base in eastern Nangarhar province “joined demonstrators and opened fire on foreign troops”, the Afghan Islamic Press news agency quoted one protester as saying.

In Mihtarlam, the capital of Laghman province east of Kabul, thousands besieged the base of a US-led military-civilian provincial reconstruction team (PRT), throwing rocks and climbing up the outer walls, police said.

“People had come from all over Laghman. They attacked the PRT, they climbed up the walls, they set fire to something there, I think a container,” police official Khalilul Rahman Niazi told AFP.

Niazi said he believed two people were wounded by gunfire from the base as they stormed the walls and hurled rocks under a pall of thick black smoke.

About 2,000 protesters also tried to march on the French base in Kapisa, east of Kabul, but were pushed back by Afghan security forces, regional police chief General Abdul Hameed Erken told AFP.

“Two protestors were slightly wounded after security forces opened fire on them,” he said.

And in northern Faryab province, there was an attempt to march on a Norwegian military base, said police chief Abdul Kahleq Aqsayee.

“A group of some 100 teenagers marched toward the base of Norwegian forces on the outskirts of the city, throwing rocks and setting fire to vehicles. They dispersed when police intervened,” he said.

Afghan President Hamid Karzai had on Wednesday called for calm as the Koran incident is investigated, and ordered his own security forces to avoid violence and protect people's lives and property.

But the Taliban, leading a 10-year insurgency against Karzai's government, on Thursday sought to exploit the anti-American sentiment.

“You should bring the invading forces' military bases under your brave attack, their military convoys, kill them, capture them, beat them and teach them a lesson that they will never again dare to insult the Holy Koran,” it said in a statement.

The Islamist movement was toppled in the 2001 US-led invasion. Nato has some 130,000 troops, mainly Americans, supporting the Karzai government.

US officials have apologised repeatedly for the burning of the Korans, which were sent to an incinerator pit at Bagram.

Nato spokesman Brigadier General Carsten Jacobson said it was “probably an act of ignorance” but “a mistake with grave consequences”.

US officials speaking on condition of anonymity told AFP the military removed Korans from a prison at Bagram because inmates were suspected of using the holy book to pass messages to each other.