Members of a Libyan army unit said they had defected and liberated the country's second city from forces loyal to veteran leader Muammar Gaddafi after scores of protesters were killed in the bloodiest revolt now shaking the Arab world.

Two residents of Benghazi told Reuters on Sunday that members of the army's Thunderbolt squad had switched sides after days of violence that mark the most serious challenge to Gaddafi's 42-year rule. Al Jazeera reported clashes in the capital between thousands of protesters and Gaddafi supporters.

Revolutions in Tunisia and Egypt have shaken the Arab world and inspired protests across the Middle East and North Africa, threatening the grip of long-entrenched leaders.

In the Gulf kingdom of Bahrain, thousands of protesters gathered in a square in Manama, calling for political change and awaiting promised talks with the island's Sunni rulers.

But after days of violence, the mood among the mainly Shi'ite protesters appeared to be more conciliatory.

Unrest also hit Yemen, Tunisia, Morocco, Oman, Kuwait, Algeria and Djibouti over the weekend as people took to the streets demanding political and economic change.