Aden, March 28 (Reuters): Saudi Arabia's navy evacuated dozens of diplomats from Yemen and the UN pulled out international staff today 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 Shia group on Aden from the east.

Riyadh's intervention, a surprise move from a conservative monarchy better known for flexing its muscle in oil markets than through military might, is planned to last a month but could extend for five or six, a Gulf diplomatic source said.

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 the city's largest ammunition depot today left at least nine badly wounded, 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. Yesterday, the Houthis and allied army units gained their first foothold on Yemen's Arabian Sea coast.