Libya's regime had its back to the wall on Wednesday as it faced NATO air strikes, the apparent defection of its oil minister and threats of prosecution by the International Criminal Court.
Rebels fighting to topple strongman Moamer Kadhafi's regime by contrast were growing in confidence and laid claim on Wednesday to being able to represent Libya at the June 8 meeting of oil cartel OPEC in Vienna.
"We want to attend, and will study the legal procedure," Mahmud Shammam, media spokesman for the rebels' National Transitional Council (NTC), told AFP in Dubai.
"We still do not know if OPEC will invite us," he said.
Oil Minister Shukri Ghanem, a veteran of Kadhafi's regime, at the weekend crossed from Libya into neighbouring Tunisia, a Tunisian official said, although there has been no confirmation he has broken ranks and defected.
Ghanem, also chairman of Libya's national oil company, had been due to attend the Vienna meeting of the Organisation of Petroleum Exporting Countries (OPEC) on behalf of the regime but he has made no comment since he left Libya and his whereabouts are not clear.
Shammam said he believed the minister was in fact already in the Austrian capital.
"We have got confirmation from several sources that Shukri Ghanem is in his house in Vienna," he said.
"He has not been in touch with the NTC, and the council is not interested, nor in need for Mr. Ghanem, but we welcome defection by any official," he added.
If the defection is confirmed, Ghanem would be among the most senior officials to abandon Kadhafi's government since an uprising erupted in mid-February.
In April, the US Treasury Department froze the assets of five senior Kadhafi regime figures, including Ghanem, in a bid to fracture the veteran ruler's inner circle.
Libya is a key crude-exporting nation but its output has been slashed since the revolt began.
According to the International Energy Agency, Libya's exports averaged 1.49 million barrels per day (bpd) before the uprising, with 85 percent of that going to Europe. Output has fallen as low as 300,000 bpd during the insurgency, although rebels plan to ramp up production.
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Meanwhile, the International Criminal Court's prosecutor warned the Libyan regime Wednesday it could face investigation and prosecution if it tries to cover up crimes committed against its people.
The office of the prosecutor sent a letter to Libyan Foreign Minister Abdelati Laabidi, its head of jurisdiction Phakiso Mochochoko told AFP in The Hague.
"The office calls upon you and other Libyan authorities to refrain from being involved in such cover up. Failure to do so will result in investigation and prosecution," said the letter, shown to AFP.
The office "considers that part of the criminal plan implemented in Libya includes the cover-up of the crimes" committed to quash a popular uprising against Kadhafi that erupted in February.
ICC Prosecutor Luis Moreno-Ocampo on Monday asked the court's judges to issue arrest warrants against Kadhafi, his second-oldest son Seif al-Islam and his brother-in-law Abdullah al-Senussi -- for crimes against humanity.
Libya's government spokesman Mussa Ibrahim has dismissed the ICC's bid, saying the court has no jurisdiction over Tripoli while denying accusations that the regime ordered the killing of civilians or hired mercenaries against them.
Thousands of people have died in violent clashes pitting regime opponents and Kadhafi loyalists, and forced some 750,000 to flee, according to data from the ICC and the UN.
French Defence Minister Gerard Longuet said in comments made public on Tuesday that NATO-led bombardments had "wiped out" Kadhafi's warplanes and heavily depleted his army.
Libya has been targeted almost daily by NATO-led strikes that began on March 19 after a UN resolution mandated a no-fly zone and called for the protection of civilians from Kadhafi's regime after he ordered his forces to crush the revolt against his four-decade autocratic rule.
NATO in its latest operation update released on Wednesday said air strikes in the vicinity of Tripoli had hit two tanks, two armoured vehicles, two surface-to-air missile launchers and two radar systems.
In Geneva, the United Nations raised its aid funding appeal to $407.8 million from $310 million to help over two million people affected by the Libyan conflict.
The sum would extend aid to September 2011, and would help 1.6 million people within Libya, as well as 500,000 others who have fled the country.
Donors have so far provided about 43 percent of the required amount, the UN said in its aid appeal report.