President Obama: 'No let up' on Col Gaddafi pressure
US President Barack Obama has said there will be "no let up" in the pressure against Libyan leader Col Muammar Gaddafi.
Speaking at a news conference with UK Prime Minister David Cameron, the US leader said that Col Gaddafi would ultimately be forced from power.
At least five explosions hit Tripoli overnight on Tuesday as Nato continued its campaign against the Libyan leader.
Russia has condemned the raids as a "gross violation" of a UN resolution.
Moscow, which did not vote for military action, said the strategy was not helping to bring about the "overall goal of quickly ending the armed conflict".
'Slow and steady'
Mr Obama, who is on a state visit to the UK, said he could not predict when Col Gaddafi would go, but that the US and its allies would "sustain the course" against him.
"I absolutely agree that given the progress that has been made over the last several weeks that Gaddafi and his regime need to understand that there will not be a let-up in the pressure that we are applying," he said.
But he warned against setting any timetable for action and cautioned against the prospect of any decisive change in the military situation on the ground.
"I believe that we have built enough momentum that, as long as we sustain the course we are on, he (Gaddafi) will step down. Ultimately this is going to be a slow, steady process in which we are able to wear down the regime forces."
Mr Cameron added that there was no future for the country - which has seen two months of intense fighting between pro and anti-government forces - with Col Gaddafi in power, and he should step down.
"The president and I agree we should be turning up the heat in Libya," he said, adding that "all options" for intensifying the pressure on the regime were being considered.
Government spokesman Moussa Ibrahim reacted angrily to Mr Obama's comments, saying that "Gaddafi's destiny, Gaddafi's future, is for the Libyan nation to decide", according to AP news agency.
"It would be a much more productive statement to say that the Libyan people need to engage in an inclusive, peaceful, democratic, transparent political process in which they can choose the shape of their political system and the leaders of their system," he said.
Air strikes late on Tuesday targeted the area around Col Gaddafi's Bab al-Aziziya compound for a second night, after similar strikes on Monday night.
Nato says the compound has been used by the regime as a base for troops and vehicles used to carry out attacks on civilians.
But Libyan authorities say Nato is trying to kill Col Gaddafi and that the night-time strikes are terrorising Tripoli residents.
The Russian foreign ministry's human rights envoy, Konstantin Dolgov, said targets which had no military use had been destroyed and that the strategy was "in no way moving us closer toward achieving the overall goal of quickly ending the armed conflict".
He added: "Air strikes are not stopping the military confrontation between the Libyan parties and only creating more suffering among peaceful civilians."
Russia has been been attempting to broker a ceasefire between the government and the rebels, and has met representatives of both sides in the past week.
South African President Jacob Zuma is to visit Libya next week for meetings with Col Gaddafi in an attempt to resolve the conflict.
Mr Zuma's office have dismissed speculation that meeting was intended to discuss an exit strategy for the leader.
The BBC's Karen Allen in Johannesburg says relations between the two countries have soured since Libya was accused last week of concealing the death of a prominent South African journalist who had been covering the crisis.
Meanwhile, African Union leaders meeting for an emergency summit in Ethiopia renewed their call for a ceasefire and a negotiated political solution to the conflict.
Libya's rebels rejected the same proposal from the AU last month, saying Col Gaddafi must step down first, and correspondents say the response is likely to be the same this time.
The rebellion against Col Gaddafi's rule began in February, spurred on by uprisings in Tunisia and Egypt that saw the presidents of those countries overthrown.