Bangkok, Sep 25 (IANS) Thai Prime Minister Prayuth Chan-ocha Thursday sent a security team to the island of Koh Tao where two British tourists were murdered last week in response to reports that an influential group of people were involved.

David Miller, 24, and Hannah Witheridge, 23, were beaten to death and their bodies found semi-naked Sep 15 near a beachside bungalow on Koh Tao island, the Bangkok Post reported.

A bloodstained hoe was found at the scene.

Police officials have said that Witheridge and Miller died from severe head injuries.

Prayuth's decision followed reports that Sean McAnna, 25, a Scottish backpacker, had fled Koh Tao claiming that his life was in danger from "Thai mafia" who wanted to kill him and frame him for the murders of the Britons.

In a new development, a police investigation team Wednesday began collecting evidence and interviewing witnesses at Lotus Bar, where McAnna was allegedly seen asking some staff to help wipe bloodstains off his body before he fled the island.

About 160 people have been questioned till date.

Police have announced a reward of 700,000 baht ($21,742) for information on the culprits.

The couple had arrived on the island Aug 25.

According to witnesses, Miller and Witheridge were seen partying on the beach with a group of about six people the night they were murdered.

Koh Tao, home to white sand beaches and azure waters, draws hordes of foreign backpackers to its "full moon" parties.