Taliban militants have killed 13 Afghan policemen in a surprise attack on a security checkpoint in the country’s eastern province of Ghazni.

The men were shot dead asleep on Friday when their checkpoint in the Andar district came under attack by Taliban militants armed with AK - 47 assault rifles, district governor Mohammad Qasim Desiwal said.

Provincial governor Mosa Khan Akbarzada confirmed the death toll and that investigation had been launched into the incident.

The victims were members of the Afghan Local Police, a village - level 18,000 - strong force established in 2010 to secure areas where the better - trained national police and army forces are scarce.

In October 2001, the United States and its allies invaded Afghanistan as part of Washington’s so - called war on terror. But over a decade into the invasion, violence continues to plague the country despite the presence of thousands of foreign forces.

On Thursday, the International Committee of the Red Cross warned that violence is increasing significantly in Afghanistan as the Taliban are stepping up their spring offensives.

Meanwhile, the United Nations says the number of civilians killed or injured in Afghanistan has dramatically increased in the first three months of 2013 compared to the same period last year.

Many civilians have lost their lives in US - led operations in various parts of Afghanistan over the past decade, with Afghans becoming increasingly outraged at the seemingly endless number of the deadly assaults.

Washington claims that its airstrikes target militants, but local sources say civilians have been the main victims of the attacks.