Thai police have detained three Myanmar men over the murder of two British tourists on the southern island of Koh Tao, saying one provided “very useful information” amid reports of a confession.

Authorities have come under increasing pressure to find the killers of David Miller, 24, and Hannah Witheridge, 23, whose battered bodies were found on a beach nearly three weeks ago.

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Scores of police officers have been deployed to the popular resort island to solve the case with DNA samples collected from hundreds of residents and several people questioned, but no arrests have been made so far.

“Three Myanmar migrant workers have been detained on the suspicion they may be involved in the murders of the tourists,” Kiattipong Khaosamang, police chief of southern Surat Thani province, told AFP on Thursday.

Media reports emerged later on Thursday that one or two of the detained men had confessed to murdering the British pair.

“He (one of the detained men) gave very useful information to us,” deputy national police chief Jakthip Chaijinda told AFP by telephone, but would not confirm that police had extracted a confession of murder.

Both police officials said they were waiting for DNA test results from the three Myanmar men.

Thai authorities frequently accuse migrants from Myanmar and Cambodia of committing crimes in the kingdom, where they make up a vast, poorly-paid and low-status workforce.

The grisly double murder has rocked the normally laid-back holiday island, which is popular with divers, and delivered a fresh blow to Thailand’s image as a tourist haven after months of political protests that ended in May’s army coup.

Critics have said police chased the wrong leads, failed to lock down the island and poorly secured the crime scene in the hours after the badly beaten bodies were found on 15 September.