BANGKOK (Reuters) - The U.S. government's decision to keep Thailand on its list of worst human-trafficking centers for an unprecedented two straight years highlights the suspected role of Thai officials in the trade despite government efforts to stop it.
The State Department's annual report on human-trafficking, published on Monday, comes days after Thailand indicted 72 people, including fifteen state officials, over suspected links to human trafficking.
Their arrests came as a result of what Thai police called their biggest-ever investigation into human trafficking.
But the crackdown in May and June came too late to be considered for the U.S. report, which covers Thai government efforts to eliminate trafficking for the year through to March.
The U.S. decision is likely to anger authorities in Bangkok after the May-June Thai crackdown led human smugglers to abandon jungle camps and interrupted the flow of migrants from Bangladesh and Myanmar through Thailand.
The State Department said Thailand's failure to investigate and prosecute officials suspected of complicity in human trafficking was one of the reasons it was not upgraded.
"Some Thai officials are complicit in trafficking crimes and corruption continues to undermine anti-trafficking efforts," the State Department said.
"In some instances, corrupt officials on both sides of land borders accept payment from smugglers involved in the movement of migrants between Thailand and some neighboring countries ... some of these migrants subsequently become trafficking victims."
While the police stepped up efforts to crack down on trafficking in May and June, the government investigated fewer human trafficking cases last year than in 2013, according to the State Department and a Thai government report.
Thailand also prosecuted fewer people and convicted fewer perpetrators of the crime in 2014.
The United States automatically downgraded Thailand, one of the oldest U.S. treaty allies in Asia, to the lowest "Tier 3" status in its 2014 Trafficking in Persons report after Thailand stayed on the report's so-called Tier 2 Watch List, the second-lowest rank, for four consecutive years.
The most senior official to face human trafficking charges is Manus Kongpan, a three-star Thai army general who surrendered to police on June 2. He denies all charges, which include human trafficking, holding people for ransom and hiding corpses.
Manus previously headed an operation to intercept migrants in the Andaman Sea for the Internal Security Operations Command, Thailand's powerful, military-run equivalent to the U.S. Department of Homeland Security.
Police General Aek Angsanont, deputy national police chief and the person in charge of the recent crackdown on the human trafficking syndicates in Thailand, said on Sunday that going after officials would be tough.
"If there are more officials involved in human trafficking then we will certainly go after them, there is no question about that, but our evidence must be very, very solid," Aek told Reuters.
The decision to keep Thailand on Tier 3 makes it the first time Thailand has languished on the lowest tier for two consecutive years since the report began in 2001.
A Reuters investigation this month raised questions about the long-term effectiveness of Thailand's crackdown on the syndicates.
Police spearheading the campaign told Reuters how they encountered official indifference about the evidence they had gathered on trafficking networks - even after the State Department downgraded Thailand in 2014 and the military government vowed to "prevent and suppress human trafficking".
And while 72 people have been arrested in the recent crackdown, experts warn the region's trafficking infrastructure is largely intact and influential figures remain at large.
Rights groups have questioned whether Thai authorities had done much more than scratch the surface with the investigation.
Sunai Phasuk, Thailand researcher at Human Rights Watch, said he was concerned the recent investigations may lose steam.
"For Thailand to prove it is genuinely sincere, it should continue pursuing a course of action that no stone will be left unturned," Sunai told Reuters.
"Thailand should continue being consistent in its crackdown against trafficking."
Editing by Simon Webb and Robert Birsel