WASHINGTON (Reuters) - Human rights groups and some U.S. lawmakers urged the U.S. government on Thursday to reconsider plans to upgrade Malaysia from the lowest tier on its list of worst human trafficking hubs, citing a lack of evidence that Malaysia had made advances against trafficking.

A man waits in a mass grave amongst coffins of unidentified remains of Rohingya people found at a traffickers camp in Wang Kelian last month, at a cemetery near Alor Setar, Malaysia, June 22, 2015. REUTERS/Olivia Harris

The comments come a day after Reuters revealed that the U.S. State Department plans to reverse last year’s downgrade of Malaysia in its annual “Trafficking in Persons” (TIP) report, a move that could smooth the way for a major U.S.-led free-trade deal with the Southeast Asian nation and 11 other countries.

Last year, the United States downgraded Malaysia to Tier 3, alongside North Korea and Zimbabwe, citing “limited efforts to improve its flawed victim protection regime” and other problems.

It was unclear why the State Department decided on the upgrade. Last year’s report said Malaysia needed to amend its anti-trafficking law and regulations, do more to protect trafficking victims, better identify victims and strengthen policies and laws with more prosecution and convictions in trafficking cases, among other recommendations.

“Without clear evidence that Malaysia has improved its anti-trafficking efforts during the past year, news that the State Department would choose to upgrade Malaysia’s TIP report ranking seems out of step with the administration’s commitment to lead in ending modern day slavery,” said Amy Sobel, a vice president at Human Rights First, an advocacy group.

Melysa Sperber, director of the Alliance to End Slavery and Trafficking, a coalition of 14 U.S.-based human rights organizations, said a Malaysian upgrade would lack credibility, would undermine the State Department’s anti-trafficking reports and would be “purely political.”

The upgrade to so-called “Tier 2 Watch List” status, which sources with knowledge of the decision told Reuters the administration had approved, removes a potential barrier to President Barack Obama’s signature global trade deal.

A provision in a related trade bill passed by Congress last month barred from fast-tracked trade deals Malaysia and other countries that earn the worst U.S. human trafficking ranking in the eyes of the U.S. State Department.

The upgrade follows international scrutiny and outcry over Malaysian efforts to combat human trafficking after the discovery this year of scores of graves in people-smuggling camps near its northern border with Thailand.

The discovery took place after the March cut-off for the U.S. report, which is expected to be released next week.

Malaysia’s Deputy Home (Interior) Minister Wan Junaidi Tuanku Jaafar has said it was unclear whether those killed were illegal migrants.

MALAYSIA WELCOMES UPGRADE

Some U.S. lawmakers and human-rights advocates had expected Malaysia to remain on Tier 3 this year given its slow pace of convictions in human-trafficking cases and pervasive trafficking in industries such as electronics and palm oil.

“Malaysia has forced labor in agriculture, construction, electronics, textiles and domestic service in homes, and was rightly given a Tier 3 ranking last year — a move we and other groups in the trafficking world supported,” Sperber said.

State Department spokesman John Kirby told a news conference that the report was not finalized, that the TIP ratings were based on pragmatic assessments and were “something we take very, very seriously.”

Malaysian Deputy Home Minister Wan Junaidi welcomed the upgrade. “Since beginning of 2014, we have been doing our best to satisfy and fulfill our obligations,” he said.

In May, just as Obama’s drive to win “fast-track” trade negotiating authority for his trade deal entered its most sensitive stage in the U.S. Congress, Malaysian police announced the discovery of 139 graves in jungle camps used by suspected smugglers and traffickers of Rohingya Muslims from Myanmar.

Malaysia hopes to be a signatory to Obama’s legacy-defining Trans-Pacific Partnership (TPP), which would link a dozen countries, cover 40 percent of the world economy and form a central element of his strategic shift towards Asia.

On June 29, Obama signed into law legislation giving him “fast-track” power to push ahead on the deal.

Senator Benjamin Cardin, ranking Democrat on the Senate Foreign Relations Committee, plans to express his concern to the White House over the planned upgrade. “It is essential that we maintain the integrity of the TIP ranking system, and the United States’ extraordinary leadership on this issue,” his spokeswoman, Sue Walitsky, said in a statement.

Democratic Congresswoman Rosa DeLauro said, “Our legitimacy and moral authority on the issue of human trafficking is being undermined in an effort to smooth the path for the TPP.”

Lawmakers are working on a compromise that would let Malaysia and other countries on the human trafficking black-list participate in fast-tracked trade deals if the administration verified they have taken concrete steps to address the most important issues identified in the annual trafficking report.

The State Department would have needed to show that Malaysia had neither fully complied with minimum anti-trafficking standards nor made significant efforts to do so to justify keeping Malaysia on Tier 3, which can lead to penalties such as the withholding of some assistance.

Phil Robertson, deputy director of Human Rights Watch’s Asia division, said he “would be shocked if Malaysia were upgraded.”

“They have done very little to improve the protection from abuse that migrant workers face. They have done precious little, frankly, to merit an upgrade,” he said.