Britain announced the end of a bloody offensive against the Taliban in Afghanistan, as a poll showed Tuesday that most Britons think military operations there are "unwinnable."

Prime Minister Gordon Brown praised the "heroic" efforts of British forces in the southern Helmand province, where the troop death toll has surged since the assault was launched late last month.

Brown claimed success in Operation Panther''s Claw in the province, as officials announced the end of the first phase of the offensive, with troops now focusing on holding ground and then bringing development to the province.

"The efforts of our troops in Helmand have been nothing short of heroic," Brown said. "There has been a tragic human cost. But this has not been in vain.

The comments Monday came as two British soldiers were killed in the region, taking the death toll since operations began in Afghanistan in late 2001 to 191, higher than the number in Iraq.

The surge in troop deaths has sparked a political row over proper resources for troops, with Brown forced to defend Britain''s strategy in Afghanistan, following calls for more equipment and boosted soldier numbers.