* NATO chief says Gaddafi weakened by bombing campaign
* NATO strikes hit government weapons depots outside Zintan
* EU considers tightening oil sanctions
* Ship burns in Tripoli harbour. Government blames NATO
By Alister Bull and Joseph Logan
WASHINGTON/TRIPOLI, May 20 (Reuters) - U.S. President Barack Obama said on Thursday it was inevitable Libyan leader Muammar Gaddafi would have to leave power and only then could a democratic transition in the North African state proceed.
Obama was speaking in a major address about the Middle East where a series of uprisings this year have toppled governments in Tunisia and Egypt, and inspired a three-month-old revolt in Libya that aims to overthrow Gaddafi after 41 years in power.
“Time is working against Gaddafi. He does not have control over his country. The opposition has organised a legitimate and credible Interim Council,” Obama said in Washington.
“When Gaddafi inevitably leaves or is forced from power, decades of provocation will come to an end and the transition to a democratic Libya can proceed,” he said, defending his decision to take military action against the Libyan leader’s government.
His comments echoed NATO Secretary-General Anders Fogh Rasmussen who said military and political pressure were weakening Gaddafi and would eventually topple him.
“Obama is still delusional,” Libyan government spokesman Mussa Ibrahim told reporters. “He believes the lies that his own government and media spread around the world ... It’s not Obama who decides whether Muammar Gaddafi leaves Libya or not. It’s the Libyan people.”
Acting under a U.N. mandate, NATO allies including France, Britain and the United States are conducting air strikes that aim to stop Gaddafi using military force against civilians.
In some of the latest strikes, NATO hit Gaddafi’s forces around 15 km (9 miles) east of the rebel-held town of Zintan in the Western Mountains region. The town and the port city of Misrata have seen some of the heaviest fighting in recent weeks.
A Reuters reporter in Zintan said NATO strikes on a government weapons depot outside the city sent plumes of smoke into the sky. Government shelling of rebel positions near the town killed at least one rebel and wounded three, a medical official in the town said.
More on Libya [nLDE72H00G]
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Graphic on Libya refugees r.reuters.com/kew39r
NATO bombs struck Tripoli, Gaddafi’s hometown of Sirte and Zlitan east of the capital, state TV said late on Thursday.
Officials later took journalists to Tripoli port where a small ship which they said had been hit by NATO spewed smoke and flames.
Rebels control eastern Libya and pockets in the west but the conflict has reached a stalemate as rebel attempts to advance on Gaddafi’s stronghold of Tripoli have stalled.
Western governments, under pressure from sceptical voters, are counting on Gaddafi’s administration to collapse.
“We have significantly degraded Gaddafi’s war machine. And now we see results, the opposition has gained ground,” Rasmussen told a news conference in the Slovak capital, Bratislava.
“I am confident that a combination of strong military pressure and increased political pressure and support for the opposition will eventually lead to the collapse of the regime.”
Libyan state TV showed footage of Gaddafi meeting a Libyan politician in Tripoli, who government spokesman Ibrahim said had been part of a delegation that met Russian officials in Moscow this week to explore possibilities for a ceasefire.
The footage zoomed in on a TV screen in the room that showed Thursday’s date displayed in the corner. The leader wore a brown robe with a hat and sunglasses.
Gaddafi was last seen on May 11 when state TV showed him meeting tribal leaders in Tripoli. NATO bombed his compound the next day, and a day later TV broadcast an audio clip in which he taunted NATO and said the alliance could not kill him.
Diplomats are watching reports that the country’s top oil official, Shokri Ghanem, has left Libya. Ibrahim denied Ghanem had defected and said he was on official business in Tunisia, some European countries and probably Egypt, and would return.
The last few days have seen a flurry of diplomatic activity focusing on a possible ceasefire deal.
But Western powers are likely to stress their determination to keep the pressure on Gaddafi when heads of state from the Group of Eight industrialised nations meet on May 27-28.
In an attempt to raise pressure on Tripoli, the European Union is considering tightening sanctions by blacklisting some Libyan ports to prevent exports of oil and imports of fuel, a Western diplomatic source told Reuters. (Additional reporting by Martin Santa in Bratislava, Isabel Coles in Cairo, Souhail Karam in Rabat, Tarek Amara and Sylvia Westall in Tunis, Matt Robinson in Zintan and Emma Farge, Peter Apps, Dmitry Zhdannikov and William Maclean in London, Writing by Matthew Bigg; Editing by David Stamp)