Last year was the deadliest on record for Afghan civilians, a UN report said, with 3,021 killed in the war.

It was an 8% increase from 2010, and 2011 was also the fifth year in a row that the civilian toll has become steadily worse.

The report said insurgents killed more than three-quarters of the civilians who died, with a steep rise in people killed in suicide bombings. It said roadside bombs were the single biggest killer of civilians, accounting for nearly one in three deaths.

Nato and Afghan security forces were responsible for 410 civilian deaths - about 14% of the total.

The figures were a grim testament to the violence that the Taliban and allied Islamist militants can still unleash in Afghanistan, even as Nato begins to map out its plan for international troops to withdraw and give Afghan security forces the main responsibility for fighting insurgents by the end of 2014.

The number of civilians killed in suicide attacks jumped dramatically to 450, an 80% increase on the previous year as militants set off increasingly powerful bombs in public places.

Insurgent-planted roadside bombs remained the single biggest killer of civilians. The homemade explosives, which can be triggered by a footstep or a vehicle, killed 967 people - nearly a third of the total. The United Nations condemned the insurgents for using the indiscriminate weapons.

"For much too long, Afghan civilians have paid the highest price of war," said Jan Kubis, the UN secretary-general's special representative to Afghanistan.

Last year was the deadliest year for Afghan civilians recorded by the UN since it started keeping a detailed civilian casualties in 2007.

Overall, 3,021 civilians died in violence related to the war. Of those, the UN attributed 77% to insurgent attacks and 14% to international and Afghan troops, while 9% were classified as unknown.