After days of sometimes acrimonious debate, ambassadors of the 28-nation alliance failed again to agree on whether NATO should take charge of an operation that has been run by a US-led coalition, a NATO diplomat said. The diplomat said the envoys would take another stab at it today, the same day European leaders gather across town in Brussels for a two-day summit, also divided over the four-day bombing campaign.

France's insistence on placing political control of the no-fly zone in the hands of a committee of coalition nations, while giving NATO a subsidiary role, has posed problems for some countries. Turkey, which has criticised the Western strikes in Libya, "doesn't want to sign on to a NATO mission while there is another coalition going on," a Western official said.

The French plan could also pose a problem for the Americans, who are eager to hand the reins to someone else but could never allow a US general to answer to both NATO and a coalition not led by the United States, the official said. Italy's foreign ministry said France was being "intransigent."

Despite the row over who should be running the broader military operations, Turkey was among a group of six NATO nations that offered 16 vessels, including three submarines, to enforce a UN arms embargo off Libya's coast. Six ships reached international waters off Libya while patrol aircraft and fighter jets headed to the area to provide long-range surveillance and intercept flights suspected of carrying weapons, NATO said.

The NATO mission has the authority to intercept and board suspicious ships, and even fire a warning shot across the bow of vessels trying to slip away, a NATO official said. Several NATO nations that are taking part in the UN-mandated no-fly zone over Libya want the military alliance to take the reins from the international coalition led by the United States, France and Britain.

The operations have been intense, with Britain saying the bombing campaign that started Saturday had almost obliterated Libya's air force, while the US military said ground troops loyal to Gaddafi were now being targeted.