Saudi Arabia's navy evacuated dozens of diplomats from Yemen and the United Nations pulled out international staff on Saturday after a third night of Saudi-led air strikes trying to stem advances by Iranian-allied Houthi fighters.

Residents reported heavy clashes between the Houthis and mainly Sunni tribal fighters in the south of the country, while the Saudi-led air campaign sought to stall a fresh offensive by the Shi'ite Muslim group on Aden from the east.

Dozens of diplomats were shipped out of Aden to the Red Sea port of Jeddah, Saudi television said, escaping the city where President Abd-Rabbu Mansour Hadi had taken refuge until Thursday, when he left for Egypt to shore up Arab support for his crumbling authority.

The director general of Yemen's Health Ministry, Al-Khadher Laswar, said more than 62 people had been killed and 452 wounded in the city since Wednesday. Explosions at Aden's largest ammunition depot on Saturday wounded nine people, he said.

In the capital Sanaa, which has been under Houthi control since September, more than 100 UN staff were evacuated, a United Nations source said. Airport staff said dozens of other foreigners working for international oil companies and NGOs also flew out to Ethiopia and Djibouti.

Houthi fighters seeking to overthrow the Western- and Saudi-backed Hadi have continued to make gains since the Saudi-led coalition launched air strikes against them on Thursday.

On Friday, the Houthis and allied army units gained their first foothold on Yemen's Arabian Sea coast by seizing Shaqra, 100 km east of Aden, allowing them to open a new front to march on the south's main city