In the last fortnight Thai police have rounded up more than 250 Myanmar Rohingya and Bangladeshi migrants following the discovery of dozens of graves in secret jungle camps run by people smugglers.
Many were abandoned in desperate conditions in the remote southern jungle bordering Malaysia after smugglers fled following the crackdown.
"Police have already indicted 187 on illegal entry charges... so those cases are being processed now," deputy national police chief Aek Angsananont told AFP from southern Thailand.
He added that a committee of officials and police were scrutinising whether 63 others are victims of human trafficking.
Rights groups have long urged Thailand to offer asylum to Rohingya migrants fleeing persecution in western Myanmar, something Bangkok has so far resisted.
Those caught being smuggled through Thailand are usually arrested as illegal immigrants and taken to detention centres where they languish, sometimes for years.
Some have been deported back to the Myanmar border where rights groups say they routinely fall again into the hands of traffickers.
In recent months Thailand has said genuine victims of human trafficking -- as opposed to economic migrants -- will not be prosecuted.
The country's junta chief, Prayut Chan-O-Cha, has mooted the idea of temporary camps for migrants.
But any camps would likely be immensely unpopular with many Thais who fear the country becoming more of a magnet for migrants from poorer neighbouring countries.
Authorities have been at pains to show Thailand is serious about tackling people smuggling after years of accusations that they turn a blind eye to -- and are even complicit in -- the trade.
Tens of thousands of Rohingya Muslims have braved the dangerous sea crossing to southern Thailand from Myanmar in recent years, with many headed for Malaysia and beyond.
Many die at sea, but large numbers have ended up in remote camps across southern Thailand where traffickers demand up to $3,000 from relatives and friends for their release.
Thailand's crackdown appears to have disrupted that trade, with smugglers abandoning migrant-filled vessels at sea, some of which have washed up on the shores of Malaysia and Indonesia in recent days.