Yemen's Huthi rebels have made important gains in the battle for the government's last northern stronghold, advancing close to the centre of Marib city despite heavy casualties, military sources said yesterday. 

The rebels have taken full control of the northwest Kassara battlefield and made progress on western frontlines despite airstrikes by the Saudi-led coalition which backs Yemen's government, the loyalist military sources said.

Marib and its surrounding oil fields make up the last significant pocket of government-held territory in the north, the rest of which is under rebel control, including the capital Sanaa.

Fierce fighting has left at least 65 dead over the past two days alone, including some 26 loyalist personnel, among them four officers, the government sources told AFP. The Iran-backed Huthis rarely disclose their own losses.