US President Barack Obama admitted Wednesday that NATO's campaign in Libya has limits but warned pressure will mount on Moamer Kadhafi to quit, even after Russia slammed the alliance's latest bombing blitz of Tripoli.
The African Union meanwhile urged a political solution to the long-running conflict, which is expected to be one of the main themes of a G8 summit in France on Thursday and Friday, which Obama and British Prime Minister David Cameron will attend.
"Once you rule out ground forces, then there are going to be some inherent limitations to our air strike operation," Obama said, adding however that the aerial bombardment would eventually force out the Libyan strongman.
The US president told a joint news conference in London with Cameron that Kadhafi's government was under pressure in "a slow, steady process in which we are able to wear down the regime forces."
Cameron echoed Obama's view, saying "patience and persistence" were necessary in Libya.
"We should be turning up the heat in Libya. I think the pressure should be on that regime," the British leader said.
Their statements came only hours after a senior NATO military official said the Western alliance is shifting into high gear in Libya in a bid to deliver a decisive blow to Kadhafi's regime, hitting Tripoli with its heaviest bombardment to date.
NATO must "speed up the systematic destruction of Tripoli's military machine with the goal of neutralising Kadhafi's forces for good," the official said, adding allies hoped Kadhafi would fall by late June or early July.
African leaders, meanwhile, urged a political solution as they opened talks on the troubled North African state in the Ethiopian capital Addis Ababa.
And Egypt's foreign minister Nabil al-Arabi said Cairo would send Hani Khallaf as its envoy to the Libyan rebel stronghold of Benghazi to follow up on developments there and push a political solution.
"I am convinced that only a political solution can lead to a lasting peace and satisfy the legitimate aspirations of the Libyan people," said Jean Ping, head of the AU Commission, the pan-African bloc's executive body.
But the "current situation on the ground and the lack of coordination of international efforts do not favour the search for a solution," he added.
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Before the talks even opened in Addis Ababa, the office of South African President Jacob Zuma said he would visit Tripoli next week.
"President Zuma will stop over in Tripoli for a discussion with Libyan leader Colonel Moamer Kadhafi, on May 30," the presidency said in a statement.
Presidency sources said the talks would focus on Kadhafi's "exit strategy."
Zuma visited Tripoli on April 10 as part of an African Union delegation that sought to broker a truce between Kadhafi and the rebels, but their proposals foundered when the rebels insisted the strongman quit office immediately.
Two sources in the president's office, speaking on condition of anonymity, said the talks would focus on Kadhafi's "exit strategy."
"The purpose is to discuss an exit strategy for Kadhafi. The meeting is still very much in the planning stages," one official said on condition of anonymity.
A second official said South Africa was working on a transition plan with Turkey, which last month proposed a "roadmap" to end the Libyan turmoil also envisaging Kadhafi's departure.
A foreign ministry official said Turkey was ready to help any initiative to end Libya's turmoil but had had no contact so far with South Africa's leader on an exit strategy for Kadhafi.
"We have had no particular dialogue so far but it does not mean that we will not have any in the future," the official said, adding Turkey was ready to contribute to any Libya peace initiative.
Russia's foreign ministry called NATO's latest bombings of Tripoli a "grave departure" from UN resolutions on Libya that could lead to a further escalation in violence.
Moscow said the West's attempts to justify the offensive by pointing to the threats being posed to civilians by Kadhafi's regime ignored the danger of the Tripoli government digging in.
"Air strikes are not stopping the military confrontation between the Libyan parties and only creating more suffering among peaceful civilians," the ministry statement said.
Six powerful explosions struck late on Tuesday near Kadhafi's residence, targeted a day earlier by intensive NATO air strikes, an AFP journalist said.
At a refugee camp near the Tunisia-Libya border, a fire killed four people and injured one, the United Nations said.
Thousands of people have fled to the camp since violence broke out in Libya in February.