Rescue teams searching for a woman who went missing after her diving boat capsized have discovered an empty life raft.

Millie Young, 57, from Brighton, and the diving boat’s cook were still missing last night after the incident on Saturday morning.

The boat, which was part of a diving tour, capsized in rough seas.

The 57-year-old and Thai cook Samniang Chaichana are still unaccounted or after a third day of searching in the waters.

Local media reports said the boat, called the Reggae Queen, got caught in the choppy waters around the Surin Islands archipelago in southern Thailand, a tourist hotspot for diving.

Ms Young, an artist and university lecturer, had been on a holiday with family friends Jo and Phil Degregorio and their two teenage children Oska and Daisy, who are also from Brighton, the Daily Mail reported.

The diving boat had 18 people on board and 16 of them have been rescued, including Ms Young’s four travel companions, were pulled aboard a passing fishing boat and taken to safety.

On Christmas Day, Thai navy chiefs said a helicopter and dozens of ships were monitoring the area, which lies around 35 miles from the Thai mainland, but had found no signs of the two women.

Rear Admiral Pongmit Narongkul, the chief of staff of the third Naval Region said the life raft they found was empty. 

He told The Telegraph on Tuesday: “A navy patrol plane has been flying across the area to search for the two victims along with navy boats.

“An inflatable life raft was found 20 nautical miles from where the ship sank but there was nobody inside.

“The flight path search area has been expanded to the western area of the Surin Islands, with a radius of 15 nautical miles from the forecast point.

“The missing people have not been found but the search is continuing.”

In a statement, a Foreign Office spokeswoman said: "We are supporting the family of a British woman and are in contact with the local authorities after an incident in Thailand."

The Foreign Office has been contacted for an update.