WASHINGTON/KABUL – Eight Nato troops, including six Americans, have been killed in attacks in Afghanistan, the Alliance announced on Sunday.

Six NATO service members were killed Sunday in a roadside bomb attack in eastern Afghanistan. All of them were Americans, a US official said in Washington, without offering further details about the incident.

The International Security Assistance Force announced the deaths in a statement. Eastern Afghanistan is considered a hotbed of Taliban activity.

The NATO statement said the blast was caused by an improvised explosive device. The statement said NATO’s policy is to allow ‘national authorities’ to give details about the soldiers.

Another two NATO soldiers were killed by a roadside bomb and insurgents in separate attacks over the past two days in southern Afghanistan, the coalition said, without providing further details.

A surge in Afghan and coalition forces during the past two years routed Taliban fighters from many of their strongholds in the south, but the insurgents stepped up their attacks this summer to take back key areas.

The incident came as donors meeting in Japan pledged to give Afghanistan $16bn in civilian aid over four years, including the period during which foreign troops are to pull out.

Nato-led forces will hand over combat command to Afghan forces by mid-2013, followed by a withdrawal of combat troops by the end of 2014. After that, only training units will remain.

In May, US President Barack Obama and his Afghan counterpart, Hamid Karzai, signed a 10-year strategic partnership agreement outlining military and civil ties between the countries after 2014.

So far this year, 225 Nato service members have been killed in Afghanistan.

NATO has some 130,000 troops in Afghanistan fighting Taliban who were ousted from power by a US-led invasion in 2001 for sheltering Al-Qaeda leader Osama bin Laden after the 9/11 attacks.

The Taliban are particularly active in the south and the east of the country, where NATO focuses most of its firepower ahead of its planned withdrawal from Afghanistan by the end of 2014.

Improvised bombs, often made with fertiliser, are a favourite weapon of the Taliban and account for a large number of overall NATO casualties.

They also take a high toll among civilians who use the same roads, with 18 being killed in three separate attacks in the southern province of Kandahar earlier Sunday.

For the past five years the number of civilians killed in the war has risen steadily, reaching a record 3,021 in 2011 — the vast majority caused by insurgents, according to UN figures.