Libya is at the centre of a refugee crisis with tens of thousands having already fled the country — and the exodus is growing daily.
More than 140,000 people have now crossed into Egypt and Tunisia, refugee officials have said.
A UN refugee agency spokeswoman said the situation was “reaching crisis point” at the Libya-Tunisia border.
It was made more volatile, other aid officials said, with humanitarian aid workers blocked from reaching western Libya, patients reportedly being executed in hospitals, and others struck by hidden gunmen riding in ambulances.
Fleeing migrant workers were also being targeted by rebels mistaking them for mercenaries being used by the government in its attempt to quash the rebellion.
The news came as it was revealed that attempts to secure compensation from the Gaddafi regime for IRA victims have been put on hold.
DUP MP Jeffrey Donaldson said: “Our legal team have indicated the discussions with the Gaddafi regime are not continuing and will not resume until there is another government in place.”
He added that lawyers were examining whether Libyan assets seized by the British Government could be secured for victims if compensation efforts failed.
Meanwhile, governments around the world stepped up the rhetoric against Gaddafi, hoping the weight of international pressure would further loosen his grip on power — yet cracks also started to appear in the strategy to remove him as Russia ruled out imposing no-fly zones over Libya.
The British Government last night signalled that the imposition of a no-fly zone — to protect the civilian population in Libya from Gaddafi's brutal crackdown — could go ahead without the backing of the United Nations.
Foreign Secretary William Hague said that while “ideally” such action would be sanctioned by a resolution of the UN Security Council, it was not necessarily essential.
“There have been occasions in the past when such a no-fly zone has had clear, legal, international justification even without a Security Council resolution,” he said. “It depends on the situation on the ground.”
Gaddafi's son Saif dismissed the threat of foreign military intervention. “We are a united Libya and not afraid. If they attack us, we are ready,” he said.
He accused Mr Cameron of trying to orchestrate change across the Arab world, saying: “Everybody wants to be a hero, to be important in history, but history should be built on concrete.”
The United States was continuing to move naval hardware towards the region in a show of force, while diplomatic sources in Moscow called Gaddafi a “living political corpse” who should step down immediately.