Rebel fighters in Libya on Thursday launched an offensive in the western mountains near the Tunisian border, a rebel spokesman said.

Hundreds of fighters kicked off the push on the town of Ghazzaia, west of the Libyan city of Nalut, according to Col. Jumma Ibrahim. He said they are also targeting the town of Al-Josh.

The fighters shot rockets and mortars as they moved toward Ghazzaia from east of the town, Ibrahim said.

Rebel fighters last month suffered heavy casualties in a failed attempt to wrest control of Ghazzaia from forces loyal to Libyan leader Moammar Gadhafi.

Last week, rebel fighters manning hilltops in the western mountains overlooking Ghazzaia told CNN that they had been watching the government forces reinforcing their weapon stocks with heavy military machinery and rocket launchers.

Rebels have been battling government troops in a fight to oust Gadhafi, who has ruled the North African nation for nearly 42 years.

NATO has used air power to enforce a U.N. resolution protecting civilians from the regime, and world powers have been announcing their support for Libya's rebel umbrella group.

The United Kingdom on Wednesday recognized the Transitional National Council as that nation's legitimate government. The United States recently recognized the council as the "legitimate governing authority" in Libya.

British Foreign Secretary William Hague on Wednesday reiterated his stance that Gadhafi could remain in Libya if he leaves power, but added that the best thing would be for him to face justice at the International Criminal Court, which is seeking his arrest.