June 28 (Reuters) - The United States on Thursday placed Myanmar on its list of worst offenders of human trafficking and accused it of using child soldiers amid global criticism over human rights abuses by the country's military against the minority Rohingya Muslims.
Gabon, Laos, Papua New Guinea and Bolivia were also downgraded to Tier 3 from the Tier 2 Watch List in the State Department's 2018 Trafficking in Person's report, which publicly embarrasses countries into acting to curb human trafficking.
The report evaluates 187 countries and territories and ranks them into four tiers, with Tier 1 being the best and Tier 3 the worst.
The U.S. downgraded Bolivia to Tier 3 because of its failure to report investigating, prosecuting or convicting human trafficking crimes, nor did it have the resources or training to do so, according to the report.
A Tier 3 ranking can trigger American sanctions limiting access to U.S. and international foreign assistance.
The report said that children should only be removed from their family as a "temporary, last resort."
U.S. President Donald Trump's controversial immigration policy, which separates families at the U.S.-Mexico border, has raised concerns over child welfare and an increase in trafficking.
A senior state department official said that the U.S. does have screening standards in place for trafficking indicators when children cross the border unaccompanied or are separated from their parents. The official referred questions on the issue to the Department of Homeland Security.
Meanwhile, Sudan was upgraded to the second-to-worst ranking at a time of improved relations between the U.S. and Khartoum. The U.S. lifted some sanctions against Sudan in October and is considering easing more.
While the report is not meant to be influenced by geopolitical considerations, both the Trump and Obama administrations have been accused by human rights groups of prioritizing economic and security interests over human trafficking concerns.
Thailand and Pakistan were upgraded to Tier 2, among a list of nations making significant efforts to comply, the report said. Pakistan spent four years on the Tier 2 Watch List of nations deserving special scrutiny, the limit a country can remain at the second-to-worst ranking before either being upgraded or downgraded.
There were a total of 29 upgrades and 20 downgrades in this year's report, the State Department official said.
North Korea, China and Russia remained listed as some of the worst offenders. China was downgraded to Tier 3 last year.
Iran and Niger were also added to the child soldiers list, while Sudan was removed. Countries on the list can face sanctions, including restrictions on receiving U.S. military aid. Iraq was added back to the list after being removed by former Secretary of State Rex Tillerson. (Reporting by Daphne Psaledakis; Additional reporting by Matt Spetalnick and Lesley Wroughton Editing by Marguerita Choy Editing by Marguerita Choy)