BANGKOK (AP) — Thai authorities are upset about being blacklisted by the U.S. for the second year in a row for failing to do enough to combat modern-day slavery.

The State Department said Monday that labor abuses in the Southeast Asian country's seafood sector are persistent, abusive and largely ignored by the government. Those abuses have been widely documented in a series of stories this year by The Associated Press which tracked the supply chains of major U.S. retailers to Thai processors selling slave-caught seafood. Those reports have prompted rescues and repatriations of more than 800 men this year.

Thai Prime Minister Prayuth Chan-ocha said Tuesday that Thailand was working on solving the issues and that the assessment was made when his administration, which took over after a military coup last year, was beginning to address the problems.

"We just have to keep working and not to worry. It's an issue of international rules, so we'll have to follow," he told reporters. "Don't worry too much. Their assessment was up to them as they were the ones assessing, not us. We just do our job. What they said in the assessment, we fixed every part of it, but some issues are quicker to fix and some are slow."

The State Department said Monday that Thai, Burmese, Cambodian, and Indonesian men are still subjected to forced labor on Thai fishing boats.

"Some men remain at sea for several years, are paid very little or irregularly, work as much as 18 to 20 hours per day for seven days a week, or are threatened and physically beaten," the report said.

The Royal Thai Embassy in Washington, D.C. denounced the assessment, saying Thailand has made substantial efforts with concrete results to stop human trafficking.

"Significant progress has been made across the board," the Embassy said in a statement, stressing the State Department report "does not accurately reflect the reality and fails to take into account significant efforts undertaken by the Thai Government."

Those efforts include amending laws and rules, ensuring better law enforcement, streaming legal processes, prosecuting offenders and protecting victims, the Embassy said.

A coalition of 25 human rights and labor organizations, including Human Rights Watch and the AFL-CIO labor federation, said blacklisting Thailand, along with criticism from the European Union and high-profile news exposes, have put needed pressure on the country.

"This decision comes at a vital time for leveraging change from the Thai government in its anti-trafficking efforts," the coalition said in a letter to Secretary of State John Kerry.

Thailand, along with Iran, Syria and Zimbabwe, were among 23 countries receiving the lowest ranking in the annual U.S. assessment of how 188 governments around the world are fighting the flesh trade and other forms of exploitative labor. The report is the State Department's key weapon for combatting human trafficking, and comes in a politically charged annual ranking in "tiers"— Tier 1 is best, 2 means more could be done, and 3 is a blacklist that can spark sanctions.

The State Department moved Malaysia and Cuba off the blacklist and up to Tier 2 this year, drawing criticism that politics — not human rights — were a factor.

Malaysia is one of 12 nations negotiating the Trans-Pacific Partnership, the key economic plank of Obama's Asia policy, but could be banned from participating if blacklisted. And the U.S. has recently patched relations with Cuba.

Republican Congressman Chris Smith of New Jersey said the report, in its 15th year, "has careened off into a new direction where the facts regarding each government's actions in the fight against human trafficking are given almost no weight when put up against the president's political agenda."

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Mendoza in Santa Cruz, California, and Associated Press writer Matthew Pennington in Washington contributed to this report.