London  - More loss of life in the Afghanistan conflict is inevitable, but the effort undertaken in the fight against Taliban forces is worthwhile, US Vice-President Joe Biden said Thursday.

The war in Afghanistan is "in the national interest" of the US and Britain, Biden said in a BBC interview. He warned that terror groups based on the border with Pakistan could "wreak havoc" on Europe and the US.

"In terms of national interest of Great Britain, the US and Europe, [the war in Afghanistan] is worth the effort we are making and the sacrifice that is being felt," said Biden, who is currently on a European tour.

"This is the place from which the attacks of 9/11 and all those attacks in Europe from al-Qaeda have flowed - from Afghanistan and Pakistan," he added.

Asked about the high number of casualties among US and British forces in the fighting in Helmand province, Biden said: "There are more to come."

Biden was full of praise for British troops, calling them "among the best trained and bravest warriors in the world." (dpa)