Kabul - Four NATO troops in Afghanistan were killed in separate roadside bomb attacks, officials said Saturday.

The three Danish soldiers were killed and another was wounded on Friday when their armoured vehicle was blown up in Gerishk district of southern Helmand province, the Danish defence ministry said in a statement.

The wounded soldier was transported to a NATO military hospital in the region, it said.

"These soldiers died honourably, helping bring security to Afghanistan," Captain Mark Windsor, an International Security Assistance Force (ISAF) spokesman in the southern region said in a a statement.

"We remain committed to working together with the people of Afghanistan to improve security and stability in their country, the cause for which these brave soldiers gave their lives," he said.

In separate attack, a Dutch soldier was killed and another wounded by a roadside bomb in the neighbouring province of Uruzgan also on Friday, the Dutch military said.

Taliban militants took responsibility for the attacks in statements posted at their website.

The latest deaths brought to 21 the number of Danish soldiers killed in Afghanistan since the fall of Taliban regime in late 2001. The Dutch soldier was the 18th to die in country since the start of the Dutch mission.

Around 700 Danish soldiers are serving in the country under the banner of ISAF, while a total of 1,200 Dutch troops are stationed in Afghanistan. Most troops from both countries are deployed to the volatile southern region.

The insurgency has increased attacks on Afghan and nearly 70,000 international forces in recent months.

More than 280 soldiers, mostly US troops, have been killed so far this year, marking it the deadliest period for the foreign forces since the ouster of Taliban regime. (dpa)