BANGKOK, Thailand -- Two Myanmar migrant workers have retracted their confessions to killing two British travellers on a southern Thai resort island and now claim to have neither raped the female victim nor slain the pair, the men's lawyers said Wednesday.

Human rights lawyer Rasada Manurasada said the arrested men claimed they were tortured and forced to confess under police custody, allegations previously denied by the police.

Rasada said that Win Zaw Htun and Zaw Lin, both 21, sent a retraction letter to prosecutors handling their case on Tuesday. "They are asking for justice and seek to give additional testimony to the prosecutors. They insisted in the letter that they didn't commit the crimes."

The battered bodies of Hannah Witheridge and David Miller were found on a beach on Koh Tao island on Sept. 15. Police arrested the two migrant workers after weeks of pressure to solve a case that dealt the latest blow to Thailand's tourism industry, which has been struggling to recover since the army staged a coup and imposed martial law in May.

Although Thai police have said they have DNA evidence linking the two men to the crime, the investigation has attracted concern the men might be scapegoats.

Parents of both suspects flew to Bangkok on Wednesday to meet with the Myanmar ambassador to Thailand and sought to meet their sons.

"I believe that my son does not have the character to (murder). He's so young," said Tun Tun Htike, the father of Win Zaw Htun, at a news conference at the Myanmar Embassy, during which he shed tears. "I strongly believe that is impossible for him to kill such big man and woman. It is impossible."

Deputy government spokesman Maj. Gen. Sansern Kaewkamnerd told reporters the Thai government welcomed inquiries and observation from Myanmar and the U.K. on the case and said the retraction of confessions could happen in this case, like any other cases.

About 2.5 million people from Myanmar work in this Southeast Asian country, most as domestic servants or in low-skilled manual labour industries like construction, fisheries or the garment sector.

Concern that the men were tortured originated with advocates for migrant workers, who are often abused and mistreated without the safeguards of rights held by Thai citizens. But the allegations also have caught the attention of the British government, which expressed its concern earlier this month to a senior Thai diplomat in London.

Foreign Office minister Hugo Swire said he told Charge d'Affaires Nadhavathna Krishnamra that inquiries into the deaths should be "conducted in a fair and transparent way." Swire said it was vital the victims' families were kept updated, and expressed "concern about the way that the police had engaged with the media on the case." British officials were already upset that Thai media had published photos they believed violated the privacy of the victims and their families.

The Thai government declared that the diplomatic meeting was a consultation by mutual agreement, rather than a summon from the British side, which is indicative of a complaint.

London's police force announced Saturday that Scotland Yard detectives would travel to Thailand to help with the investigation.

British police said in a statement that officers would work with Thai police to ensure the killers were brought to justice in a clear and fair process.