Sana'a, Yemen - At least two men were rescued in dramatic fashion from the Red Sea, but three more were reported dead on Monday as a volcano blasted a small Yemeni island under the sea.

Warships from the NATO alliance which were heading for the Suez Canal rescued two survivors of the blast after a night in the shark-filled waters of the Red Sea, Ensign Matthew Goetz of the US Navy told Deutsche Presse-Agentur dpa via satellite phone from the sea.

But a spokesman for the rescue forces from the Yemeni naval base in the port city of Houdieda, Abdel-Bari Shamsan, told the state news agency that one man had been rescued and three bodies found.

The survivor was in a very good condition and was on a boat on the way to the military hospital in the city, he added. Forty-seven other people were evacuated from the tiny island of Jabal al-Tair and were receiving treatment in the military hospital, with one of the evacuees in a critical condition.

But the three-kilometre-long island itself has totally disappeared, Shamsan said.

The eruption hit the unpopulated island, about 100 kilometres from Houdieda in western Yemen, on Sunday evening.

The Dubai-based al-Arabya TV channel reported that eight missing personnel from a Yemeni army garrison stationed there were regarded as presumed dead.

But shortly after dawn local time, sailors on the US destroyer USS Bainbridge spotted a man in the water. The man proved to be a survivor of the eruption, 'tired from his overnight ordeal, but in good spirits,' a NATO press release said.

Soon after, the Canadian frigate HMCS Toronto, working in cooperation with the Yemeni Coast Guard, picked up a second survivor.

The search for the remaining six soldiers is ongoing, the NATO statement said.

Yemen has had a garrison on the island since 1996 following a dispute with Eritrea over the nearby Hanish and Zuqar islands.

Yemen's Minister of Oil and Minerals Khaled Bahah told the state news agency that the 'increasing' volcanic activity on the island was first registered on Friday after a mild earthquake measuring 3.7 on the Richter scale struck off the coast of the mountainous island.

The agency said eight army troopers were missing in a landslide that was triggered by the earthquake.

The minister did not rule out an eruption from the island's highest mountain at 1,200 metres.

He said it remained 'unclear' whether an eruption would occur.

Seismologists say the island sits on a faultline in the southern part of the Red Sea. The last volcanic eruption was in 1883.

The water of the southern Red Sea is at its warmest at this time of year, making it physically possible for humans to survive in it for extended periods. However, the region is home to several large species of shark, some of which can be dangerous to humans.