David Miller and Hannah Witheridge
David Miller and Hannah Witheridge were found dead om Thai island Koh TaoFacebook

British brothers Christopher and James Ware have been allowed to leave Thailand after their DNA was found to not match murdered tourists David Miller and Hannah Witheridge.

The brothers, from Jersey in the Channel Islands, had been ordered to remain in Bangkok after Miller and Witheridge were found dead on a beach on the island of Koh Tao on 15 September.

On 17 September, police ruled out 12 suspects of the brutal attack and are now searching for men who may have shared a cigarette with the pair before their deaths

Investigators found DNA on a cigarette butt that matched DNA discovered on Witheridge's body.

Christopher, 25, was stopped as he was about to leave Suvarnabhumi Airport on 16 September and questioned after police found what they believed was a pair of his blood-stained trousers in Miller's luggage, reported the Bangkok Post.

He had been staying in the same room as Miller but police later said there was no evidence against him or his brother.

At an earlier press conference, police admitted they were no closer to finding the killers and it was not known whether the suspects were still on the holiday island or had fled to mainland Thailand.