By Alister Bull
WASHINGTON (Reuters) - The United States on Saturday backed the Arab League's call for the U.N. Security Council to impose a no-fly zone over Libya, and Washington said it was preparing for "all contingencies."
"We welcome this important step by the Arab League, which strengthens the international pressure on Gaddafi and support for the Libyan people," the White House said in a statement.
The Arab League earlier on Saturday asked the council to impose the no-fly zone, giving a regional seal of approval that NATO has said is vital for any military action.
The U.S. statement stopped short of directly endorsing military intervention, maintaining the cautious approach Washington has taken to avoid appearing to lead the drive to oust Libyan ruler Muammar Gaddafi.
Critics of the policy accuse the Obama administration of foot-dragging as lives are being lost.
"The international community is unified in sending a clear message that the violence in Libya must stop, and that the Gaddafi regime must be held accountable," the White House said.
"The United States will continue to advance our efforts to pressure Gaddafi, to support the Libyan opposition, and to prepare for all contingencies, in close coordination with our international partners," it said.
NATO said on Thursday strong Arab support was one of the factors needed for action on a no-fly zone to police Libyan air space. It also said more planning was needed, together with a U.N. mandate.
The United States has said a no-fly zone remains an option to put pressure on Gaddafi, while emphasizing the need to carefully plan any intervention and weigh potential fallout.
Obama told a White House press conference on Friday the world community was "slowly tightening the noose" on an increasingly isolated Gaddafi, but made plain he would not lightly send U.S. troops into harms' way.
The United States, which would likely be expected to take a leading role in enforcing a no-fly zone, has significant military resources within striking distance of Libya.
But U.S. officials also have gone to considerable lengths to stress that it could be a costly exercise with uncertain results and unintended consequences.
(Reporting by Alister Bull; Editing by Xavier Briand)