The International Transport Workers Federation is calling on Fiji and the Philippines to uphold and protect the rights of seafarers.
A group of Filipino sailors stranded in Fiji - some for up to three years - have been allowed to leave the country.
The plight of the 20 men was highlighted last year after allegations of fraud and human trafficking were made against their employer - Goundar Shipping Ltd.
The Filipino seafarers accused the company of abusive treatment including not being paid.
The group claimed they were brought to Fiji on false promises by Goundar in 2018 but ended up working in unsanitary, unsafe conditions for seven days a week.
The Filipinos also claimed the company held back their passports and refused to get them tickets home after they raised concerns about their situation.
The group sought the help of the International Transport Workers Federation (ITF) which called for an investigation into the operations of Goundar Shipping in Suva and the agent that sent the workers to Fiji - Able Maritime in Manila.
The ITF said the failure by the Fiji and Philippines governments to enforce the seafarers' employment contracts, and guarantee their basic workers' and human rights, left the Filipinos trapped working against their will in Fiji for years.
"We complained through the human rights commission in Fiji as well as a police investigation that was opened up as well as a department of labour and immigration investigation.
"But our immediate concern was getting the workers back to the Philippines and getting them out of a situation that they were effectively being homeless in a foreign country."
The ITF said while all the Filipino seafarers were now safely back home, the unions would continue to put pressure on the Fiji and Philippines governments to 'do the right thing'.
"Fiji and the Philippines both have a huge opportunity to clarify to the world that they are places where human rights are upheld, where workers' rights are upheld.
"They have obligations with the International Labour Organisation, with the United Nations, with bilateral arrangements they have with countries like New Zealand to uphold the integrity of the human rights and workers' rights."
The ITF is close to red-listing Able Maritime, said the unions' Inspectorate Coordinator Steve Trowsdale.
The ITF launched its directory of agents in August this year as part of its ITFShipBeSure.org initiative to help seafarers find safe and secure jobs.
In the Philippines, a seafarer must register with a manning agent to work overseas. The agent is then responsible for ensuring the seafarer's earnings make it back to their family.
To help seafarers avoid the rogue agents, the ITFShipBeSure.org website ranks agents as green (good to go) or red (best to avoid).
The ITF censure is accompanied by a message from its network of 134 inspectors and 670 affiliated unions across more than 150 countries.
"In three entirely different parts of the world, Filipino seafarers have found themselves being paid much less than they signed up for in Able Maritime contracts," Trowsdale said.
"These seafarers have been trapped into working conditions well below the minimum we would expect and, in some cases, below what national and international laws allow.
"Manning agencies have duty to protect the seafarers that they place in work, and to get them home if conditions prove unsatisfactory or the jobs were advertised in a misleading way. At least three times in as many months, Able Maritime has fallen well short."
Goundar Shipping and Able Maritime have both denied the claims made by the seafarers and the unions.