On the eve of the first meeting of an international contact group, a spokesman for the rebel Transitional National Council said it will accept nothing short of the removal of Gaddafi and his sons from the country.
Mahmud Shammam, whose council is seeking international approval, stressed: "We want to move from the de facto recognition of the council to an internationally-recognised legitimacy."
Such recognition would pave the way for the TNC to receive billions of dollars of desperately needed Libyan funds frozen in the United States and Britain, and the right to obtain credit at sovereign rates.
Libya's former foreign minister Mussa Kussa will be present in Doha, but rebels made it clear he would not be representing them in any way at talks ahead of the meeting.
An African Union peace plan for Libya was left in tatters on Tuesday after rebels stuck to their demand that Muamer Gaddafi step down and NATO came under pressure to drop more bombs on the strongman's forces.
The Libyan opposition's Transitional National Council will address the contact group as an alternative voice for Libya's people.
In London on March 29, the TNC was not permitted to attend the plenary session of an international ministerial conference on the crisis, although its envoys held bilateral talks with several world powers on the sidelines.
Since London, with Gaddafi continuing to defy NATO air strikes and with mounting calls for him to quit, the opposition council has gained support and recognition, notably from France, Italy and Qatar.
The rebels were keen to distance themselves from Kussa, the former foreign minister.
"He's not connected to (the) Transitional National Council in any way or shape," media liaison official Mustafa Gheriani told AFP.
The African Union peace plan looked to be dead in the water after rebels dismissed a ceasefire out of hand.
Having managed to secure Gaddafi's agreement to a truce, the AU delegation encountered resistance from the rebel leadership in Benghazi, who argued that the initiative was obsolete and insisted Gaddafi be forced to quit.
In Benghazi, rebel leader Mustafa Abdul Jalil said the African initiative did not go far enough.
"From the first day the demand of our people has been the ouster of Gaddafi and the fall of his regime," he said.
"Gaddafi and his sons must leave immediately if they want to be safe... Any initiative that does not include the people's demand, the popular demand, essential demand, we cannot possibly recognise." The rebels also doubted Gaddafi would adhere to a truce.
"The world has seen these offers of ceasefires before and within 15 minutes (Gaddafi) starts shooting again," TNC spokesman Shamsiddin Abdulmolah said.
With outgunned rebel forces making little headway in their bid to oust Gaddafi's regime, British Foreign Secretary William Hague urged NATO allies to intensify military operations in Libya.
"We must maintain and intensify our efforts in NATO, that is why the United Kingdom has in the last week supplied additional aircraft capable of striking ground targets threatening the civilian population of Libya," Hague said.
"Of course it would be welcome if other countries also do the same," he said in Luxembourg before a meeting of EU foreign ministers. "There is always more to do."
Thousands of lives had been saved thanks to air strikes that were launched by Western powers on March 19. These prevented Gaddafi's forces from storming Benghazi, Libya's second largest city, three weeks ago, Hague said.
"A huge amount has been achieved in Libya but clearly there is more to be done," he continued. "Of course, to have any viable, peaceful future for Libya, Colonel Kadhafi needs to leave."
His comments came after his French counterpart, Alain Juppe, had said France's NATO allies were not pulling their weight in Libya and their forces should do more to help destroy Kadhafi's heavy weaponry.
"NATO must fully play its role, and it is not doing so sufficiently," the minister told France Info radio, adding that France would bring the matter up with EU ministers on Tuesday and with NATO in Berlin on Thursday.
On the ground, there were reports that rebels and Gaddafi forces have again clashed in the mountainous western region around Zintan.
And in Luxembourg, TNC official Ali al-Isawi said Gaddafi's troops had killed 10,000 people since the rebellion broke out in mid-February, with another 30,000 wounded and 20,000 missing.
There was no way to independently confirm those figures.