Protesters hold pictures of Zaw Lin and Win Zaw Tun as they demonstrate in front of the Thai embassy in Yangon on Friday.

AFP/Yangon

Hundreds of protesters demonstrated outside Thailand's embassy in Yangon on Friday after two Myanmar migrants were sentenced to death by a Thai court for murdering two British backpackers, in a verdict that has sparked anger in their homeland.

Zaw Lin and Win Zaw Tun were found guilty on Thursday of killing David Miller, 24, and the rape and murder of Hannah Witheridge, 23, whose battered bodies were found on a beach on the southern Thai diving resort of Koh Tao in September last year.

The grim killings have sullied Thailand's reputation as a tourist haven and raised questions over its justice system after the defence accused the police of bungling their investigation and using the men as scapegoats - a charge authorities deny.

Hundreds of people, including monks, gathered in Yangon to protest the verdict, many saying they believed the two men had been wrongly convicted.

"This is just discrimination against us," demonstrator Min Thein Khaing told AFP.

"There was little evidence, no witnesses and not much DNA evidence but still they got a death sentence. It's unfair."

Many held signs with English slogans such as "Save Myanmar Poor Boys" and "Free Our Innocent Citizens". Others held aloft pictures of Thailand's King Bhumibol Adulyadej, saying they were appealing to him for clemency.

A police cordon stopped protesters demonstrating opposite the embassy itself, confining them to the end of the street instead.

‘Regret over verdict’

The rally came as Myanmar's ambassador in Thailand met with senior government officials.

"After hearing the verdict, as a human being I felt regret but it's a judicial matter that still has to proceed," ambassador Win Maung told reporters through a translator.

"I hope this case will receive special care and won't affect bilateral ties."

Thailand has warned its citizens to take care in Myanmar following the verdict.

Thai prosecutors and police insist their evidence against the men was rock solid, including DNA found on Witheridge's body.

But the defence, which has vowed to appeal the verdict, disputed the forensic evidence, saying it was improperly collected and processed.

They also accused the police of torturing their clients into signing confessions, which they later retracted.

Amnesty International has called on Thai authorities to fully investigate the torture allegations, something the rights group said had yet to happen.

Activists say the case reflects a wider trend of low-paid migrant workers from neighbouring countries being blamed for crimes in Thailand where the justice system is easily bent by wealth and power.

Hundreds of thousands of low-paid migrants from Myanmar, Cambodia and Laos prop up key industries in Thailand such as the tourism and fishing sectors, often experiencing well documented abuse and discrimination.

However the Thai authorities have received an endorsement from David Miller's family who backed investigators after the verdict was announced, saying they believed the evidence against the two accused was "overwhelming".

The court in Koh Samui also dismissed the defence's torture allegations.