NATO says five of its troops have been killed in improvised-bomb attacks in southern and eastern Afghanistan.

Three soldiers died in separate attacks Saturday, and NATO officials said a single explosion killed two others on Friday.

Two of the casualties were British troops fighting in Helmand province; two others were identified as Americans, and NATO did not disclose the nationality of the person killed in the third fatal bombing on Saturday.

Roadside bombs, also known as improvised explosive devices (or IEDs), are a major cause of troop deaths in Afghanistan.

Meanwhile, raids by Afghan and coalition forces in Helmand collected nearly two tons of processed heroin, 800 kilograms of opium and 90 kilograms of ammonium nitrate - a common ingredient in home-made bombs.  

That quantity of drugs would be worth nearly $40 million if they were smuggled out of Afghanistan.

NATO troops also detained several suspected insurgents in Helmand and Kandahar province overnight while pursuing two senior Taliban commanders.

Some information for this report was provided by AP and AFP.