Western and Arab nations are to meet in the United Arab Emirates to discuss how events in Libya might develop if Col Gaddafi were no longer in power.
The so-called Contact Group is also expected to firm up its pledge to set up a fund to help the Libyan rebels.
The meeting comes as Nato intensified its air strikes on government targets in Tripoli.
Meanwhile, 14 rebels were reportedly killed in the city of Misrata as they tried to push back government troops.
Health officials and a rebel spokesman said more than 20 others were wounded when government forces responded with heavy artillery fire.
In a separate development, the chief prosecutor for the International Criminal Court (ICC) said there was evidence that Col Gaddafi had ordered the rape of hundreds of women as a weapon of war against rebel forces.
And in Geneva, the UN Human Rights Council is due to debate a report on alleged human rights violations allegedly committed by both government troops and the rebels.
'End game'
Top government officials from the Contact Group - which includes Britain, France and the US, as well as Arab allies Jordan, Kuwait and Qatar - will be meeting in Abu Dhabi later on Thursday.
US Secretary of State Hillary Clinton has already arrived in the UAE.
Ahead of the talks, a senior US official was quoted by Reuters as saying that "the international community is beginning to talk about what could constitute [an] end game" to the Libyan conflict.
"That would obviously include some kind of ceasefire arrangement and some kind of political process... and of course the question of Gaddafi and perhaps his family is also a key part of that," added the official, who spoke on the condition of anonymity.
British Foreign Office Minister Alistair Burt, who is also expected to attend the talks, said that "the contact group will also reiterate the unequivocal message... that Gaddafi, his family and his regime have lost all legitimacy and must go so that the Libyan people can determine their own future".
"Until Gaddafi does so, the pressure will increase across the board: economically, politically and militarily," Mr Burt said.
At least two powerful explosions rocked Tripoli late on Wednesday.
It was not immediately clear what was targeted in the air strike, but it reportedly happened close to Col Gaddafi's residence.
Last week, Nato extended its air operations for another 90 days and increased the scope of its UN-mandated campaign to protect civilians. Since then, attack helicopters have gone into action and command centres in Tripoli pounded.
Viagra pills
The report the UN Human Rights Council will debate in Geneva on Thursday contains what the authors say is evidence of war crimes - including murder, torture, and indiscriminate attacks on civilians - committed by the Libyan regime, and of serious violations by rebel forces too.
Col Gaddafi is sending government representatives from Tripoli to answer the charges in this report after his usual diplomatic team to the UN in Geneva defected en masse in February.
On Wednesday, the ICC's chief prosecutor Luis Moreno-Ocampo said he was looking into allegations that hundreds of women had been raped on Col Gaddafi's orders.
Mr Moreno-Ocampo said rape was a "new aspect of repression" by Col Gaddafi's regime.
The prosecutor said he was also looking at possible evidence that pro-Gaddafi security forces had been given medication such as Viagra to enhance their sex drive.
In March, a Libyan woman, Eman al-Obeidi, made headlines around the world after she burst into a Tripoli hotel and said she had been raped by Col Gaddafi's troops. She is recovering at a refugee centre in Romania.
Testimony from captured Libyan soldiers that rape was used as a systematic weapon of war was taken by the BBC's Africa correspondent Andrew Harding in May.
There has so far been no comment on the allegations by the Libyan authorities.
Last month, Mr Moreno-Ocampo asked ICC judges to approve arrest warrants for Col Gaddafi, his Saif al-Islam, and intelligence chief Abdullah al-Sanussi.
