Swathes of Libya have fallen to opposition control and others into lawlessness, residents and reporters said, as opponents of veteran leader Moamer Kadhafi vowed to march on the capital and topple him from power.

State television said Kadhafi would soon make an address to residents of Zawiyah city west of Tripoli, two days after he broke cover to urge his supporters to crush the insurrection.

The television gave no further details.

The European Union said it was seeking naval back-up to rescue up to 6,000 trapped Europeans as tens of thousands scrambled to escape what former colonial ruler Italy said was a "bloodbath" in the oil-rich north African state.

Italy, the nearest major European country, warned of a looming "catastrophic humanitarian crisis" as migrants flee north Africa.