Gulf Arab states have offered to mediate to end anti-government protests in Yemen.

Following an extraordinary meeting in Riad, the Gulf Cooperation Council called on “all parties concerned to return to dialogue to work out the reforms required.”

Violence erupted on Sunday night in the city of Taiz, south of the capital. Police are reported to have fired live rounds, that doctors said killed five people and wounded dozens more. In the port city of Hudaida, armed men in civilian clothes opened fire on protesters, witnesses said. There was no immediate word on casualties there.

Anti-government protesters have camped out around Sanaa University since early February.

However, in the past two weeks, President Ali Abdullah Saleh has mobilised thousands of his own supporters.

The United States, a key ally of the president, has not commented publicly but Yemeni and US officials now reportedly say Washington is preparing to withdraw its backing.