Hundreds of protesters demonstrated outside Thailand's embassy in Yangon 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 at 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.

The rally came as Myanmar's envoy 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."

Other Myanmar officials have said they intend to support the two men's appeals.

"The judicial process is not over yet, we have much to do such as discussing with respective persons from Thailand and appealing to the High Court," Hmuu Zaw, manager of the President's Office, posted on Facebook.


Evidence disputed

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 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.

A statement from Witheridge's family that was released after the verdict did not mention whether they thought the convictions were safe.

Defence lawyers visited the death row inmates on Friday.

"They seemed in good spirits, very strong," Andy Hall, an advisor to the defence team who was on the visit, told AFP. "They repeated that the truth will come out in the appeal and that they are confident they'll be released."

The pair will soon be transferred to a high security prison on the mainland, he added.