* Libyan rebels say military chief killed
* Anti-Gaddafi forces claim towns near Tunisian border
* Opposition wins more foreign support
* Rebels sell last of oil, Austria aims to unfreeze funds
By Michael Georgy and Rania El Gamal
NALUT/BENGHAZI, Libya, July 29 (Reuters) - Libya’s rebels said their military chief was shot dead on Thursday, a blow to Muammar Gaddafi’s rivals as they launched a military offensive in the west and won further international recognition of their cause.
The rebels said Abdel Fattah Younes, who was for years at the heart of the Gaddafi government before defecting to become the top military leader in the rebellion in February, was shot dead by assailants after being summoned back from the battlefield.
Younes was not trusted by all of the rebel leadership due to his previous role and the circumstances of his death were unclear, but it is likely to be a severe blow to a movement that has won the backing of some 30 nations recognising the Benghazi-based movement.
The rebels claimed to seize several towns in the Western Mountains on Thursday but they are struggling to make a serious breakthrough. With the prospects fading of a swift negotiated settlement, both sides seem prepared for the five-month war to grind on into the Muslim holy month of Ramadan in August.
A rebel official said no deal was worth talking about unless it meant Gaddafi and his powerful sons left Libya, while the veteran leader vowed to fight on “until victory, until martyrdom”.
After a day of rumours, rebel leader Mustafa Abdel Jalil confirmed that Younes had been summoned before a rebel judicial committee investigating military issues but he and two bodyguards were shot before he could appear before it.
It was not clear where the trio were killed and, adding to the confusion, Jalil did not say how he knew they had been killed, adding only that their bodies were yet to be found.
Shortly afterwards, gunmen burst into the grounds of the hotel where Jalil was speaking and fired bursts of shots in the air, a Reuters reporter said. No one was hurt.
At least four explosions rocked the centre of Tripoli on Thursday evening as airplanes were heard overhead.
The killing of Younes, who was involved in the 1969 coup that brought Gaddafi to power and then became his interior minister, came after the rebels attacked Ghezaia, a town near the Tunisian border held by Gaddafi throughout the war.
By late afternoon, the rebels said they had taken control of the town, from which Gaddafi forces had controlled an area of the plains below the mountains.
“Gaddafi’s forces left the areas when the attack started,” said rebel fighter Ali Shalback. “They fled towards the Tunisian border and other areas.”
Reuters could not go to Ghezaia to confirm the report, as rebels said the area around the town could be mined. But looking through binoculars from a rebel-held ridge near Nalut, reporters could see no sign of Gaddafi’s forces in Ghezaia.
Juma Ibrahim, a rebel commander in western mountains, told Reuters by phone from town of Zintan that Takut and Um al Far had also been taken in the day’s offensive.
Rebels have taken swathes of Libya since rising up to end Gaddafi’s 41-year rule.
They hold northeast Libya including their stronghold Benghazi, the western city of Misrata and much of the Western Mountains, their closest territory to the capital.
Yet they remain poorly armed and often disorganised.
“We can beat Gaddafi now, we have captured more weapons from the Libyan army, mostly rockets and AK-47s,” said Mohammed Ahmed, 20, a market trader turned fighter.
The fighting has led to a stalemate in a conflict that Gaddafi has weathered for five months, despite a rebel advance and hundreds of NATO air raids on his forces and military infrastructure.
A recent flurry of diplomatic activity has yielded little, with the rebels insisting Gaddafi step down as a first step and his government saying his role is non-negotiable.
Western suggestions that Gaddafi might be able to stay in Libya after ceding power appeared to fall on deaf ears.
U.N. envoy Abdel Elah al-Khatib visited both sides this week with plans for a ceasefire and a power-sharing government that excludes Gaddafi, but won no visible result.
The rebels said any deal that did not envisage Gaddafi and his sons leaving the country was “not worth talking about” while the Libyan leader appeared defiant on Wednesday, urging rebels to lay down their arms or suffer an ugly death.
At a briefing to the U.N. Security Council in New York, Lynn Pascoe, who heads the body’s political department, said both sides had been posturing since discussions began, and added:
“Both sides are willing to talk, but they are still emphasising maximum demands at this point, and patience is clearly required before detailed discussions can begin.”
The rebels received a further boost on Thursday when Portugal followed Britain in recognising them.
London has also unblocked 91 million pounds ($149 million) in frozen assets, joining the United State and about 30 other nations who have now recognised the opposition, potentially freeing up billions of dollars in frozen funds.
Austria said it wanted to unfreeze up to 1.2 billion euros ($1.7 billion) of Libyan money and transfer it to the rebels, but needed legal papers to show that a financial body set up by the NTC amounted to a valid central bank “identical to the one in Tripoli” to whom the money had belonged.
The cash-strapped rebels, who control Libya’s oil-rich east, have been selling fuel to raise urgently-needed funds, but are unable to pump new supplies because of war disruption.
A tanker carrying crude oil has sailed from Benghazi for Italy, as the rebels sell the last of their stockpile, industry sources and ship tracking data said on Thursday.
An NTC official said senior rebel leader Mahmoud Jibril was on a visit to Qatar but declined to say what he was doing there.
Additional reporting by Rania El Gamal in Benghazi, Hamid Oul Ahmed in Algiers, Missy Ryan and Lutfi Abu Aun in Tripoli, Andrei Khalip in Lisbon, Olesya Dmitracova and Ikuko Kurahone in London, Sylvia Westall in Vienna, Humeyra Pamuk in Dubai and Patrick Worsnip in New York; Joseph Nasr in Berlin, Ahmed Tolba in Cairo; writing by David Lewis and Richard Meares ; editing by Myra MacDonald