Libyan leader Muammar Gaddafi on Friday threatened Europe with retaliation for a NATO-led military campaign, saying he will send hundreds of soldiers to launch attacks there.

"Hundreds of Libyans will martyr in Europe," Gaddafi told a multi-thousand-strong crowd in Sabha some 500 miles south of the capital Tripoli in a speech shown on national television, adding that NATO will regret "when the war moves to Europe."

The threat came as insurgents suffered casualties on Friday after a massive attack by NATO aircraft.

Gaddafi pledged to use the "eye for an eye and tooth for a tooth" principle, adding that he and his supporters are ready to "become martyrs and fight until the end."

Libya has been rocked by fighting between pro- and anti-Gaddafi forces since mid-February.

An international military operation in Libya began on March 19, following a UN resolution authorizing countries "to take all necessary measures" to help protect Libyan civilians from attacks by Gaddafi forces, and was extended until late September.