The EU is a big market for imported poultry processed in Thailand. Swedwatch's report says about 270,000 tonnes of poultry meat products were shipped from Thailand to the EU in 2014, and Thailand is Sweden's biggest poultry supplier after Denmark.

The two organisations looked into the effects of this consumption on the source country.

They found that a shortage of labour within Thailand had led to migrant workers coming in from neighbouring countries, mainly Cambodia and Myanmar, lured by the prospect of better wages to send money back home.

However, the report found that many of these migrant workers are exploited by employers and recruiters. Swedwatch said that such labour rights violations were similar to those exposed in other Thai industries in recent years.

Workers are indebted due to a range of recruitment fees, and have had their personal documentation such as passports and work permits confiscated, the report says.

"Extortionate recruitment fees, coupled with confiscation of personal documentation, at worst signal forced labour," said Sonja Vartiala, Finnwatch's executive director.

Finnwatch and Swedwatch conducted the research at six factories that process broiler meat belonging to four Thai companies. The four companies were Charoen Pokphand Foods (CPF), Laemthong, Centaco and Saha Farms Group.

CPF Group, which produces broiler for Scandinavian companies S-Group, Lejos, Sodexo and Findus products, stood out positively from the rest, despite some problems for example regarding social security payments.

Other factories had more problems, Finnwatch and Swedwatch reported. For example, at a factory belonging to the Centaco Group, recruitment agencies made arbitrary deductions from workers' salaries. Laemthong Group has been in court for forging work permits and visas, and a factory belonging to Saha Farms Group is charging fees to the workers for the use of protective equipment.

"Workers reported very similar problems at all factories covered in our investigation. It looks clear that meat importers' monitoring of working conditions in their supply chains has failed," Ms Vartiala said.

Many importers of Thai broilers expect that their suppliers respect labour rights in their operations. But requirements for suppliers are vague and the monitoring of their implementation is unconvincing, Finnwatch and Swedwatch said.

For the consumer it is difficult to find out about working conditions in the meat supply chain, as they will not always even know that they are eating Thai broiler products. In processed meat products, the origins of the meat do not need to be disclosed.

Instead of calling for consumer action, Finnwatch is therefore calling for action by the decision-makers.

"Thai broiler industry is yet another example of the need to introduce mandatory human rights due diligence for companies. Workers' rights should be taken into account alongside food safety and quality considerations," Ms Vartiala said.

Finnwatch's statement added that it is most concerned about companies that do not transparently disclose their suppliers, saying that Subway was the only company that did not disclose even the country of origin of its broiler meat. Dr Oetker Finland and Findus also did not disclose the names of all of their Thai broiler suppliers.