International diplomats are gathering in Istanbul to discuss a political solution to the civil war in Libya, whose leader Moammar Gadhafi has reiterated a vow to fight to the end against rebels trying to end his 42-year rule.

Diplomats expected to attend Friday's talks in the Turkish city include U.S. Secretary of State Hillary Clinton, envoys of other NATO members, and representatives of Gulf and African nations and Libya's rebel movement. It will be the fourth meeting of the Contact Group on Libya since March, when the Libyan uprising began.

Turkey and the African Union each have proposed peace plans to end the Libyan civil war.

Washington and its NATO allies want Mr. Gadhafi to step down immediately to allow Libya to begin a democratic transition. They say their four-month-long campaign of airstrikes on pro-Gadhafi forces will continue as long as those forces keep attacking Libyan civilians.

Mr. Gadhafi said Thursday he will never give in to the rebels or their NATO allies. In a message broadcast by loudspeaker to supporters in the town of Al-Ajaylat, he also called French President Nicolas Sarkozy a “war criminal.” France was an early contributor to the NATO mission.

Mr. Gadhafi's prime minister, Al-Baghdadi Al-Mahmoudi, also announced a symbolic end to economic cooperation with Italy, Libya's former colonial ruler and another participant in the NATO airstrikes. Mr. Al-Mahmoudi said Tripoli no longer will work with the Italian government or Italian oil giant ENI, one of the biggest investors in the Libyan oil sector.

ENI already had stopped its oil production in Libya and deliveries of Libyan natural gas to Italy several months ago. ENI's Libyan assets are split between the government-controlled region around Tripoli and the rebel-held regions in the east and west.