"NATO's decision to assume command and control of the no-fly zone, in addition to the arms embargo already being enforced, is a significant step forward and will ensure that the alliance's tried and tested machinery is used to best effect," a Downing Street spokesman said.

He also welcomed the decision by the United Arab Emirates to contribute 12 planes to the no-fly zone, saying it was "evidence of the real and tangible Arab role, building on the leadership the Arab League as a whole showed when they originally led calls for a no-fly zone over Libya."

The NATO and UAE decisions late Thursday "demonstrate the strength and breadth of the coalition involved in protecting the people of Libya", he said.

"Britain welcomes both of these important developments. They reinforce international efforts to implement UNSCR (UN Security Council Resolution) 1973 and protect the people of Libya," he said.

The UN resolution authorised all necessary measures to implement a ceasefire and no-fly zone to protect civilians in Libya from Moamer Qadhafi's forces.

NATO members agreed Thursday to enforce the no-fly zone "to protect civilians" but held off military action against Qadhafi's forces, after days of fraught negotiations.

Britain had been urging the 28 member military alliance to take command of Libyan operations as soon as possible.