The US and Britain have raised the prospect of arming Libya's rebels if air strikes fail to force Muammar Gaddafi from power.
At the end of a conference on Libya in London, Hillary Clinton, the US secretary of state, said for the first time that she believed arming rebel groups was legal under UN security council resolution 1973, passed two weeks ago, which also provided the legal justification for air strikes.
The British foreign secretary, William Hague, agreed that the resolution made it legal "to give people aid in order to defend themselves in particular circumstances".
But Clinton admitted the Americans "do not know as much as we would like to" about the interim national council (INC). In Washington, Admiral James Stavridis, Nato's supreme allied commander in Europe, told the Senate that intelligence analysis had revealed "flickers" of al-Qaida or Hezbollah presence inside the movement, and argued it required further study.