More than 300 Rohingya were discovered on Tuesday in a building in the town of Sadao, while a second raid on Thursday at a rubber plantation near the border town of Pedang Besar uncovered 393 more, including 14 children and 8 women.
"These illegal migrants have been handed over to immigration authorities and will be deported back to Myanmar," Police Colonel Krissakorn Paleetunyawong, deputy commander of police in the area, told Reuters.
An estimated 800,000 Rohingyas live in Myanmar but are officially stateless. The Myanmar government denies them citizenship, regarding them as illegal Bangladeshi immigrants, but Bangladesh does not recognize them as citizens either.
Hundreds make their way abroad each year by boat, especially to Malaysia, in search of a better life, an exodus given added impetus after recent sectarian violence between minority Rohingyas and majority Buddhist in Myanmar's western state of Rakhine.
The raids in southern Thailand were led by the army and police as part of what they call anti-human-trafficking operations.
"The Rohingyas were en route to Malaysia and the camp we found was used as a holding facility by middlemen paid to facilitate their journey," said Lieutenant Colonel Katika Jitbanjong of Padang Besar police station.
Last week, Thai authorities found 73 Rohingya boat people adrift near the holiday island of Phuket.
They sent the asylum seekers, who arrived in rickety and overcrowded boats, back to sea in Thai fishing boats, New York-based rights group Human Rights Watch said.
Various rights groups called then for the Thai government to scrap its policy of summarily deporting Rohingyas who land up in Thailand. In two separate incidents in 2008, the military pushed 992 Rohingya boat people back to sea without food and water and hundreds may have died, activists have said.
The United Nations estimates about 13,000 boat people, including many Rohingya, fled Myanmar and neighboring Bangladesh in 2012, a sharp increase from the previous year.
Thailand and Singapore refuse to provide asylum to members of the Muslim minority group while Bangladesh has closed its border to them.
"Thailand should scrap its inhumane policy of summarily deporting the Rohingya, who have been brutally persecuted in Burma, and honor their right to seek asylum," said Sunai Phasuk of Human Rights Watch.
(Editing by Alan Raybould and Robert Birsel)