British Foreign Secretary William Hague demanded that Moamer Kadhafi step down but said the Libyan leader may be allowed to remain in the North African country.
Speaking ahead of talks in London with French counterpart Alain Juppe, Hague said Britain would prefer for Kadhafi to quit Libya and stressed that France and Britain were "absolutely united" in NATO's current mission against Kadhafi.
"What is absolutely clear, as Alain (Juppe) has said, is that whatever happens, Kadhafi must leave power," said Hague.
"Obviously him leaving Libya itself would be the best way of showing the Libyan people that they no longer have to live in fear of Kadhafi.
"But as I have said all along, this is ultimately a question for Libyans to determine," added Hague.
Juppe said the allies were in "perfect co-operation" over the UN-sanctioned mission, which began in March, despite suggestions in France that the mission was dragging on too long.
"We think that we must continue to exert strong pressure on the Libyan regime with the same methods," he said.
"If we did not intervene four months ago it would have been a massacre in Benghazi and I think we may be proud to have taken this courageous decision," concluded Juppe, referring to a rebel stronghold.
Libya on Monday accused NATO of killing at least seven people in an air raid on a medical clinic in Zliten east of Tripoli, as top US officer Admiral Michael Mullen spoke of "stalemate" in NATO's campaign.
"We are, generally, in a stalemate," Mullen told a press briefing in Washington billed as his last before retirement.
Mullen said NATO has "dramatically attrited (reduced) his forces" and "additional pressure has been brought," even if Libyan strongman Moamer Kadhafi has not been ousted.
"In the long run, I think it's a strategy that will work... (toward) removal of Kadhafi from power," Mullen said.
Libya's insurgents on Monday accused Kadhafi's forces of shelling the rebel-held city of Misrata, targeting gas and oil facilities and setting them on fire, in a statement received by AFP.
The reported NATO air strike on the small clinic in Zliten occurred between 8:00 and 8:30 am (0600-0630 GMT), a local official told an AFP correspondent on a guided media tour of the western town.
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The foreign journalists saw a completely destroyed building with a crescent sign at its entrance and the ground littered with surgical gloves, oxygen bottles, pharmaceuticals and stretchers, but no victims.
In other parts of Zliten the reporters were shown three damaged food storage buildings and another still on fire, which the government minders also blamed on NATO.
Strewn around the site were hundreds of smouldering bags of rice, tomatoes and vegetable oil, as firefighters tried to extinguish the flames. Residents said the strike occurred at around 3:00 am (0100 GMT).
In the same compound, journalists saw a completely destroyed building bearing the name "Agricultural Security."
The minders spoke of other air strikes that caused "civilian casualties" early on Monday, but did not elaborate.
East of Zliten, the reporters toured a deserted neighbourhood and saw damage to a school and a mosque. Heavy artillery and explosions could be heard in the distance, and a local official said this came from a NATO warship.
A rebel statement, meanwhile, appealed for help to put out fires in the coastal enclave of Misrata, Libya's third city, caused by loyalist shelling.
"The loyalist forces shelled strategic regions inside Misrata, hitting gas and oil warehouses," the statement said, adding that speedy assistance was needed to extinguish the fires "threatening civilians."
Zliten lies about 150 kilometres (100 miles) east of Tripoli, Kadhafi's stronghold, and 60 kilometres (35 miles) from rebel-held Misrata.
The tour of Zliten came after rebel forces repulsed a counter-offensive by Kadhafi loyalists southwest of the capital.
Regime troops had attacked the western desert hamlet of Gualish on Sunday and shelled the region before pulling back under rebel rocket fire as NATO warplanes flew overhead, an AFP correspondent reported.
The insurgents, who have been fighting to oust Kadhafi since mid-February, recaptured Gualish this month and are planning to use it as a springboard for a western assault on Tripoli.
They said their campaign to attack the capital from the east has been slowed by efforts to remove an estimated 45,000 landmines from around the oil town of Brega.
"We have no choice. We have to clear the sand of mines," Mohammed Zawawy, a spokesman for the Union of Revolutionary Forces in Ajdabiya, told AFP.
He estimated the number of Kadhafi troops still inside Brega at no more than 1,000.
Meanwhile, Ibrahim al-Furis, a Libyan diplomat declared persona non grata in Bulgaria, refused to leave the country on Monday and with other staff organised a minor rebellion at the embassy in Sofia, denouncing Kadhafi's regime.