Two British Royal Air Force Chinook helicopters landed in Luqa this afternoon, augmenting the RAF effort which already includes two Hercules transport aircraft.

The large Chinooks are seen as ideal aircraft for rescuing people in areas where there are no runways, such as the desert.

Both Britain and Malta have spoken of the difficulties they face in evacuating workers from desert oil rigs.

Such heavy-lift aircraft have also been used for resupply operations and the insertion of special forces.

Britain's Sky News reported today that British Special Forces troops have been put on standby to conduct deep penetration rescue missions to take British subjects out of isolated Libyan oil exploration camps following widespread criticism of the UK government's response to the unfolding crisis.

Sources told Sky that the Special Boat Service (SBS) had already forward mounted liaison officers to a Mediterranean location, which Sky would not reveal, as part of the preparations to rescue an estimated 170 people unable to reach Tripoli where RAF Hercules aircraft have been evacuating civilians.

Any mission to fly into Libyan airspace on a rescue mission would be extremely dangerous and Libya has highly efficient air defences, although some may have fallen to rebel hands.

There have been reports of oil workers being menaced by local armed militia and even some incidents of looting of their food and equipment.

"If groups of mercenaries are going to get close to Brits in Libya and threaten to kill or capture them, then we obviously would be making plans to deal with that, and those would include a powerful military option," a source told the TV channel.

Meanwhile, Malta International Airport continued to be a busy transit point for the air evacuation of workers from Libya this morning, and at one time aviation enthusiasts enjoyed the rare simultaneous presence of three Boeing 747 Jumbo Jets on the tarmac, although one of them was a freighter whose visit was not related to the events in Tripoli.