It has one of the largest fishing fleets in the world and much of the catch from Thailand's fishing boats ends up on Japanese, European and American plates. Yet the industry stands accused of profiting from slave labour.

The BBC's Becky Palmstrom investigates this tale of modern day slavery. She travels to Thailand and Myanmar to find out why and how illegal migrants are being forced onto Thai fishing boats, many of them working for months unpaid. She hears allegations of cruelty and even murder.

In Thailand Becky meets Ken, from rural Myanmar, who hoped to make a better life for himself and his ageing parents. He ended up being trafficked twice onto Thai fishing boats. The BBC team was able to bring his parents, back in Myanmar, the first news they had had of their son for four years.

The Thai authorities admit that most of their fishing fleet is unregistered and much of it relies on illegal migrant labour. The Thai government insists it is making every effort to clamp down on trafficking and forced labour in its fishing industry. Yet the US State Department has recently downgraded Thailand to Tier 3 in its "Trafficking in Persons Report (TIP)" - a measure of how little it believes Thailand is doing to curb the problem.

Producer: John Murphy.