Breaking: Ten children, two soldiers and a policeman killed in Afghanistan suicide blast

20 other students were wounded in explosion near a marketplace

Ten children and one policeman have died after a suicide attack outside a busy market in eastern Afghanistan.

Two members of the US-led military coalition were also killed, but their nationalities have not been released.

Children were just leaving a local school for lunch when the bomber, on a motorbike, detonated his explosives outside the market in Samkani district as American forces passed, according to General Zelmia Oryakhail, provincial police chief of Paktia province.

The Afghan Ministry of Interior did not say the ages of the children. Oryakhail also told Reuters that 20 people were wounded in the attack.

Taliban insurgents have recently unleashed a wave of suicide bombers to hit government targets and international agencies in the country, and militants have been attacking police checkpoints in several provinces in a major test for the security forces of President Hamid Karzai's government.

Elsewhere, a landmine killed seven Afghan civilians in the eastern province of Laghman. Recently, insurgents have littered the country's roads with the devices, and roadside bombs that often kill civilians. A statement from the provincial government said a group of four women and two children had gone with a male driver into the hills to collect firewood. On their way back, their vehicle hit the mine and all inside were killed.

The Afghan army and police are this year fighting the insurgency with little or no help from international forces that have been in Afghanistan since the 2001 US-led invasion.

All NATO combat missions will finish by the end of next year, and the 100,000 foreign troops deployed across Afghanistan have already begun to withdraw from the battlefield.

More than 11 years after the Taliban regime was ousted in 2001, efforts to seek a political settlement ending the violence have so far made little progress, but pressure is growing ahead of the 50-nation coalition's withdrawal.

The US provides the bulk of the military presence, with 68,000 troops, with the UK's 9,000 the second most.

As the withdrawal looms, there are tentative parallel efforts to encourage negotiations with the insurgency. The Taliban has confirmed that it sent a delegation to Iran for three days of talks, signaling that Tehran could be seeking the role of regional mediator in negotiations to end its neighbor's 12-year war.

Spokesman Qari Yousef Ahmadi said in an email that emissaries from the Taliban's political office met with Iranian officials over the weekend. He said a separate group of Taliban clerics attended a religious conference in Tehran - an unprecedented development, since the Sunni Muslim Taliban have long been enemies of Iran's ruling Shiite clerics.