Libya accused Britain of damaging an oil pipeline in an air strike, hours after rebels said government attacks had halted production of oil they hope to sell to finance their uprising.
"British warplanes have attacked, have carried out an air strike against the Sarir oilfield which killed three oilfield guards and other employees at the field were also injured," Deputy Foreign Minister Khaled Kaim told reporters.
Kaim said the strike damaged a pipeline connecting the oilfields to the Marsa el Hariga port. "There is no doubt this aggression … is against international law and is not covered by the U.N. resolution," he said.
Any damage to a pipeline leading to Marsa el Hariga is likely to cause more harm to the rebels than to Muammar Gaddafi.
The Liberian-registered tanker Equator sailed from the port, near Tobruk, on Wednesday, apparently with the first cargo of crude sold by rebels since their uprising began in February.
A rebel spokesman had said Gaddafi artillery hit rebel-held oilfields in Misla and the Waha area on Tuesday and Wednesday, halting production.
The rebels regained ground around the oil port of Brega on Wednesday but repeated accusations NATO was not doing enough to help them as Gaddafi's forces unleashed yet more mortar rounds, tank fire and artillery shells on the western city of Misrata.
A French minister said NATO air strikes in Libya risked getting "bogged down" and a top U.S. official warned U.S. lawmakers Libyan agents could be inside the United States and might try to launch retaliatory attacks.
"We want to make certain that we've identified these individuals to ensure no harm comes from them, knowing they may well have been associated with the Gaddafi regime," FBI Director Robert Mueller said.
Gaddafi himself appealed for a halt in the air campaign in a rambling three-page letter to U.S. President Barack Obama bluntly dismissed by Secretary of State Hillary Clinton.
"Mr. Gaddafi knows what he must do," Clinton told a news conference with Italian Foreign Minister Franco Frattini, reiterating calls for a ceasefire, the withdrawal of his forces from cities they have stormed and his departure from Libya.
Rebels who control eastern Libya are angry at what they perceive to be a scaling back of operations since NATO took over an air campaign, after an early onslaught led by the United States, France and Britain tilted the war in their favour.
French Foreign Minister Alain Juppe said Gaddafi forces were making it harder for alliance pilots to distinguish them from civilians by hunkering down in populated areas. "The situation is unclear. There is a risk of getting bogged down," he said.
Civil war in the vast North African desert oil producer ignited in February when Gaddafi tried to crush pro-democracy rallies against his 41-year rule inspired by uprisings that have toppled or endangered other autocrats across the Arab world.
NATO ON THE DEFENSIVE
Rebel criticism has put the Western military alliance on the defensive, particularly over Misrata. Spokeswoman Carmen Romero said that "the pace of our operations continues unabated. The ambition and the position of our strikes has not changed".
NATO air strikes are targeting Gaddafi's military infrastructure but only to protect civilians, not to provide close air support for rebels, much to their dismay, as part of a no-fly zone mandated by the U.N. Security Council.
Relieving the siege of Misrata was a NATO priority but alliance officials conceded that Gaddafi's army was proving a resourceful and elusive target.
