The teenage son of a British man is believed to have died after going missing during a Malaysian diving trip.

Adrian Chesters, 46, told the coastguard his son Nathen, who has Dutch nationality, had become too weak and died while they were adrift.

Mr Chesters and an 18-year-old French woman were rescued on Saturday, two-and-a-half days after going missing.

They had been taking part in a group dive off the coast of Mersing, in the southern state of Johor.

French National Alexia Molina, 18, and Mr Chesters were spotted at night by local fishermen around 50 miles south of where they went missing on Wednesday.

Police said they were both reported to be in a stable condition after being taken to hospital by the marine authorities.

Their diving instructor Kristine Grodem, 35, who is Norwegian, had previously been rescued.

She said that when the group surfaced from their dive they were unable to see their boat, and that the currents then separated them.

The Malaysian coastguard said it had been able to speak to Mr Chesters, who had told them Nathen had become too weak to hold out and died while they were adrift.

The Indonesian authorities are now expected to continue the search for the teenager's body.

A Foreign Office spokesman said it was in contact with local authorities and stood ready to assist the British man.

The boat operator who took the group to the dive site was detained after testing positive for drugs, police said.

The group had been on a training dive in 49ft (15m) deep water near the small island of Pulau Tokong Sanggol, around 10 miles (16km) off the coastal town of Mersing on Wednesday.

The alarm was raised after they did not return about an hour into the dive.

The divers' disappearance came days after Malaysia reopened its border to foreign nationals on 1 April.