Thai police have charged two migrant workers from Myanmar with the murder of Mr David Miller, 24, and the rape and murder of Ms Hannah Witheridge, 23, after the tourists' battered bodies were found on the southern island of Koh Tao on September 15.

Police have said the men confessed to the crime and their DNA matched samples taken from Ms Witheridge's body.

But unease over the case has deepened amid reports that the suspects were tortured into confessing -- an allegation Thailand has strongly denied.

British Ambassador Mr Mark Kent told AFP he was meeting with the Thai police, foreign ministry officials and his Myanmar counterpart, without giving further details.

Before the meeting an official from the Myanmar president's office in Naypyidaw told AFP he hoped the talks "would help bring a fair and genuine investigation" into the case, which many have accused Thai authorities of mishandling.

"We hope Thai authorities will act with balance and accuracy to prosecute the offenders according to the law and not take action wrongly against those who didn't commit the crime," he said, requesting anonymity.

On October 13, the British government summoned Thailand's top diplomatic representative in London to stress "real concern" about the handling of the investigation.

In a statement junior foreign minister Mr Hugo Swire "reiterated that the UK police stood ready to assist with the investigation and subsequent legal process".

It is unclear if Thailand has responded to the offer of help.

The arrests followed intense scrutiny of Thai authorities, which had been accused -- in criticism led by the British media -- of bungling the investigation in the days after the crime.

The grisly murders on the normally tranquil Thai island delivered a fresh blow to the kingdom's image as a tourist haven after months of political protests that ended in May's army coup.