THE distraught family of a young British woman murdered along with a man in Thailand have arrived in the country, as police revealed DNA found on her body did not match any of their suspects.

Relatives of Hannah Witheridge, whose body was found on a beach alongside fellow British victim David Miller, hugged each other as they prepared to meet Royal Thai Police at their headquarters in Bangkok.

Miss Witheridge, 23, and 24-year-old Mr Miller were found with severe head wounds on the island of Koh Tao on Monday.

Tests carried out on a group of Burmese migrants questioned over the deaths have shown no DNA matches, police said.

DNA discovered on the body of Miss Witheridge has also been found not to match British brothers Christopher and James Ware, who spoke to officers.

Neither of the Wares, who are thought to have shared a room with Mr Miller in Thailand, was declared a suspect in the investigation but they had been interviewed and asked to remain on the island by Thai police.

DNA traces from possible suspects could not be detected on Mr Miller's body because it was smeared with his blood, assistant national police chief General Jarumporn Suramanee said.

Amid mounting criticism, Thailand's military ruler yesterday apologised for suggesting foreigners visiting the country's world-famous beaches would be unsafe wearing bikinis.

General Prayuth Chan-ocha's comments triggered an uproar after he claimed that foreigners visiting the Southeast Asian country think "they can do whatever they want, wear bikinis wherever they like ... (but) will they be safe?"

He was quoted as saying: "Can they be safe in bikinis ... unless they are not beautiful?"

Mr Prayuth said he had not meant to criticise anyone and said the country was safe for tourists.

In the face of mounting criticism Mr Prayuth said: "I apologise that I have spoken too harshly ... I didn't mean to criticise or look down on anyone. Today I can guarantee that Thailand is still safe ... I wanted to warn (the tourists) to be careful."

Royal Thai Police on Wednesday insisted they had found "strong evidence" in connection with the deaths and the group of migrants were questioned after bloodstains were found on some of their clothes.

But detectives revealed no matches were found between them and two sets of DNA found on Miss Witheridge's body and on a cigarette butt discovered near the scene of the murders.

Police said post-mortem examinations had shown Miss Witheridge died from head wounds while Mr Miller died from severe blows to the head and drowning.

Mr Miller, from Jersey, also suffered wounds on his hand, indicating a struggle had taken place.

A bloodstained garden hoe, believed to be the murder weapon, was found nearby.

More than 70 Thai police have been questioning migrant workers and tourists on the island, visiting hotels, bars, homes and businesses as they search for the killer.

Mr Miller and Ms Witheridge met each other on the island of Koh Tao while staying in neighbouring rooms at the Ocean View Bungalows resort, at the southern end of the main Sairee beach on the island's west coast.

In a statement following her death, the family of Miss Witheridge, from Great Yarmouth in Norfolk, said they were "heartbroken" and "utterly devastated".

"She was selfless and caring and made each and every day that little bit more wonderful," they said.

Mr Miller had just finished studying civil and structural engineering at Leeds University in June, where he was on course to achieve a first-class degree.

He had left Jersey on July 18 to undertake a six-week work placement as part of a scholarship at a mining company in Australia before travelling on to Thailand for a break with a close friend. He had been due to leave Thailand this week.

In a statement published after his death, his family said: "David was an artist by temperament, so talented. He had a creative eye that he carried with him through life and in his degree.

"He was hard-working, bright and conscientious, with everything to look forward to.

"David was very giving to his family and friends and we all adored him. He will be sorely, sorely missed."