"This decision sends a clear message to the Gaddafi regime: we are determined to continue our operation to protect the people of Libya," said NATO Secretary-General Anders Fogh Rasmussen. Gaddafi is trying to withstand the NATO air barrage and put down a rebellion among his own people.
British Foreign Secretary William Hague welcomed the extension, saying it was an "important reaffirmation" of the world's commitment to protect Libyan civilians.
In Rome, meanwhile, Libyan oil chief Shukri Ghanem said he had defected and now supports the rebels, a major blow to the Libyan leader.
"In this situation, which is unbearable, one cannot continue working," Ghanem told reporters at a Rome hotel. He said he now united himself with the "Libyan youth" who were fighting to build a constitutional democracy in the country.
In Brussels, NATO and its partners in the military campaign to protect Libyan civilians decided to extend their mission for another 90 days, the military alliance's top official said Wednesday.
Wednesday's decision came during a meeting of ambassadors from the 28 NATO countries plus ambassadors from the five non-NATO countries participating in the Libya campaign - Jordan, Qatar, Sweden, the United Arab Emirates and Morocco - said Carmen Romero, the NATO's deputy spokeswoman.
The military alliance took over command of the operation on March 31 after difficult negotiations among its members. Unanimity of 28 is required for action, and the operations to enforce a no-fly zone and use air power, based on a UN Security Council resolution that calls for the protection of civilians, were authorised for an initial 90 days.
That time would have expired on June 27. The decision to extend the campaign was taken nearly a month ahead of time to allow the participating countries to do their internal planning, Romero said.
NATO also is enforcing a UN arms embargo against Libya. That part of the operation has no time limit.
Critics have charged that the military campaign has turned into a stalemate and said it is difficult to dislodge a government through air power alone. But NATO, while maintaining that regime change is not its goal, says it has significantly diminished Gaddafi's ability to attack civilians.
Fogh Rasmussen said in a statement that the extension of the campaign carries a message not only for Gaddafi but for the Libyan people.
"NATO, our partners, the whole international community, stand with you," he said. "We stand united to make sure that you can shape your own future. And that day is getting closer."
