(Reuters) - Thai police on Friday found at least 30 graves believed to belong to migrants from Myanmar and Bangladesh at what authorities say is an abandoned trafficking camp in remote jungle in Thailand's south, police said.

Illegal migrants, many of them Rohingya Muslims from western Myanmar and from Bangladesh, brave often perilous journeys by sea to escape religious and ethnic persecution and to seek jobs in Malaysia and Thailand, a regional human trafficking hub.

Four bodies had been exhumed so far, said Police Colonel Anuchon Chamat, deputy commander of Nakorn Si Thammarat Provincial Police. A total of at least 30 graves were found in a "well set up" smuggling camp.

"There are at least 30 graves that have been place marked. We exhumed four bodies today and will continue to exhume bodies," Anuchon told Reuters in a telephone interview.

The graves were the first discovery of its kind in Thailand, said Anuchon.

Two other bodies that had not been buried and were left to rot in the open were also found, he said. One survivor was rescued from the abandoned camp and taken to hospital in nearby Pedang Besar.

Around 200 soldiers, police and rescue workers were at the site on Friday, said Sathit Kamsuwan, a volunteer rescue worker.

The discovery highlights the brutal nature of the trafficking trade in which hundreds are believed to have died in camps or at sea.

Every year, thousands of Rohingya and Bangladeshi boat people arrive in Thailand, brought by smugglers. Many are taken by road to camps in the jungle, where traffickers demand a ransom to smuggle them south across the border to Malaysia.

Last year, Thailand was downgraded to the lowest tier on the U.S. State Department's influential Trafficking in Persons (TIP) Report, which annually ranks countries by their anti-trafficking efforts.

(Editing by Nick Macfie)