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.

The court convicted Zaw Lin and Win Zaw Htun of the murder of David Miller, 24, and the rape and murder of Hannah Witheridge, 23, on the Thai holiday island of Koh Tao in 2014.

The case has been mired in controversy amid questions about the police investigation and Thailand's treatment of migrant workers.

Around 1,000 people gathered in front of the Thai embassy, calling for the two to be freed. Dozens of police stood guard and closed a lane in front of the building.

Some protesters held signs saying: "Shameless Thailand government" while others shouted, in English, "We want justice."

Still others held aloft pictures of Thailand's King Bhumibol Adulyadej, saying they were appealing to him for clemency.

"We are here just to demand justice for the two Myanmar nationals who were unfairly sentenced to death," poet Aung Khun Sat said. "We feel that the court decision is unfair and that there was no transparency in the court hearing."

During the trial prosecutors built their case around DNA evidence that police said linked the two migrant workers to the crime. Defense lawyers argued that police had mishandled the DNA evidence and that the two men were tortured while in detention.

The killings sullied Thailand's reputation as a happy-go-lucky tourist destination and raised questions over its justice system and its treatment of migrant workers.

U Win Maung, Myanmar's Ambassador to Thailand, said the verdict would not affect diplomatic ties.

"Everyone who is a human, if they hear that they are getting the death sentence, they will be sad, but this is the legal procedure so we have to adhere to the legal procedure," U Win Maung told reporters in Bangkok.

Some activists argue that the defendants were scapegoats. Thailand hosts about 2.5 million migrants from its poorer neighbor, many of them working in the fishing and construction industry or as domestic helpers or cleaners in hotels and restaurants.

Amnesty International called for an independent investigation into allegations the Myanmar men were tortured, adding that police in Thailand had a "long and disturbing track record" of using torture to extract "confessions."

A judge dismissed allegations of torture in the Koh Tao case saying there was no evidence it took place.

bik/msh (Reuters, AFP, dpa)