Police say preliminary DNA tests results from two British brothers do NOT match Hannah Witheridge who was murdered on a Thai beach.

The bodies of Hannah and another British tourist David Miller were found on Koh Tao on Monday.

Some 11 Burmese migrants on the island of Koh Tao had been arrested after bloodstains were found on some of their clothes by police.

However, investigators are under renewed pressure after DNA tests on the group also failed to bring any matches.

Additionally, the results indicated that that semen discovered on Miss Witheridge's semi-naked body does not belong to David Miller.

This could undermine a previous theory that the two victims had been having sex on a beach shortly before their deaths, considered a taboo in the deeply religious country.

On Wednesday night, police had confirmed there was forensic evidence to suggest that the 23-year-old woman, from Great Yarmouth, might have been raped.

Officers have said that full DNA results will be released later today.

Miss Witheridge and Mr Miller were found in the early hours of Monday morning. Both had sustained head wounds, and a bloodstained garden hoe - believed to be the murder weapon - was found nearby.

It has been revealed that Mr Miller, a 24-year-old from Jersey, died from drowning in conjunction with a blow to the head, while wounds on his hands indicates a struggle had taken place.