Police are awaiting the results of DNA tests after finding “strong evidence” in the hunt for the killer of two Britons brutally murdered in Thailand.

The semi-naked bodies of David Miller, 24, and 23-year-old University of Essex student Hannah Witheridge were discovered on a beach on the island of Koh Tao on Monday.

A spokesman for the Royal Thai Police said 11 Burmese migrants have been questioned over the deaths, after blood stains were found on some of their clothes.

Two British brothers have also been spoken to, after police said they “cannot rule out” anyone from their investigation until DNA test results are made available tomorrow.

James Ware and his brother Christopher are from Jersey, where Mr Miller grew up, and are understood to have shared a room with him in Thailand, according to reports.

The two Britons are not in custody but they are being escorted by police, the spokesman said.

Police Colonel Kissana, deputy police spokesman, said: “We have strong evidence that led us to the Burmese suspects as blood stains were found some of their clothes. DNA tests are being completed and we should hopefully have a report tomorrow.

“We have got to do whatever it takes to obtain concrete evidence.”

The spokesman added that police found forensic evidence suggesting Miss Witheridge might have been raped.

Officers are also looking at the possibility that the two victims were having sex on the beach shortly before their deaths, considered a taboo in the deeply religious country, he said.

Mr Miller and Ms Witheridge suffered deep wounds to the head and face.

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

Major General Pornchai Sutheerakune, head of the Thai Institute of Forensic Medicine, 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 also suffered wounds on his hand, indicating a struggle had taken place, police said.

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.

The families of both victims have paid tribute to them.

Ms Witheridge was described by her family as “a beautiful, intelligent, loving young woman who poured joy into the lives of all who knew her”, while Mr Miller was a “hard-working, bright and conscientious” young man who would be “sorely, sorely missed”.

In a statement, Ms Witheridge’s family said: “She was selfless and caring and made each and every day that little bit more wonderful.

“Our family are utterly devastated and shocked by what has happened to our beautiful Hannah. To lose her in the way that we have is beyond comprehension.

“We are heartbroken and no words can possibly describe how we feel. As such, we would be extremely grateful to be left in peace while we come to terms with our loss.”

Mr Miller’s 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.”

British consular officials from the Thai capital Bangkok have travelled to the island to liaise with local officials.

A Foreign Office spokeswoman said: “We are aware of reports that the Thai police have spoken to British nationals in connection with the case. The investigation is a matter for the Thai authorities.

“We stand ready to provide consular assistance if required.”