DUBAI (AFP) - Clashes between rebels and Yemeni government fighters killed at least 111 in Marib in three days, pro-government sources said, following a renewed offensive by Houthi insurgents.

The fighting between Thursday (June 24) and Sunday killed 29 pro-government personnel and at least 82 rebels, the pro-government sources told Agence France-Presse.

"These areas witnessed fierce fighting amid artillery shelling from both sides and intense coalition air raids," a government military official said, referring to the Saudi-led military coalition that backs the government.

The Iran-allied Houthi insurgents escalated their efforts to seize Marib, the government's last stronghold in northern Yemen, in February, and the fighting has killed hundreds on both sides.

Control of the oil-rich region would strengthen the Houthis' bargaining position in peace talks, but the battle has also raised fears of a humanitarian catastrophe, as many Yemenis had fled to the area to escape fighting in other parts of the country.

Yemen's conflict flared in 2014, when the Houthis seized the capital Sanaa, prompting the Saudi-led intervention to prop up the government the following year.

The fighting has killed tens of thousands and left some 80 per cent of Yemenis dependent on aid, in what the United Nations calls the world's worst humanitarian crisis.

The war has also displaced millions of people and left many on the brink of famine.