London - The US and their allies face a "strategic stalemate" in parts of Afghanistan, British Foreign Secretary David Miliband warned Friday.

He said a "bigger and more effective" security force was needed to stop the Taliban controlling more territory and repeated the call for other European nations to increase troop levels in Afghanistan.

"In parts of the country there is a strategic stalemate," Miliband said in a BBC interview.

However, this was not caused by the Taliban "overwhelming our forces" because the insurgent would lose any conventional encounter.

"But they are a terrorist insurgency force which is able to do grave and grievous damage to our own troops and others."

Miliband praised the contribution of Denmark and the Netherlands, who like Britain have troops in southern Afghanistan, but said the burden should be shared more equally by other European Union countries. (dpa)