When heavy shelling from ground troops loyal to Libyan leader Muammar Gaddafi drove rebels out of the key oil port of Ras Lanouf on Wednesday, some coalition members began to discuss the possibility of arming the opposition.

The rebel, armed mostly with light weaponry and riding in pick-up trucks, said they were overwhelmed by the rocket bombardment from government forces and had to give up Ras Lanouf, a Mediterranean town in northern Libya.

The withdrawal slowed the rebels' advancement along the coastal road toward the nation's capital of Tripoli.

Airstrikes have neutralized Gadhafi's air force and pounded his army, but his ground forces remain far better armed, trained and organized than the opposition. Rebels have few weapons more powerful than rocket-propelled grenades and machine guns, and are no match for Gaddafi's tanks and longer-range heavy weapons.

British Prime Minister David Cameron said, meanwhile, that his government has not precluded arming the retreating rebels.

"We do not rule it out but we have not taken the decision to do so," Cameron told the House of Commons.

He said the U.N. resolution imposing a no-fly zone and an arms embargo on Libya do not necessarily rule out providing weapons to the rebels.

Under the U.N. resolution authorizing necessary measures to protect civilians, nations supplying weapons would need to be satisfied they would be used only to defend civilians -- not to take the offensive to Gadhafi's forces.