A boat was found on Koh Rawi in Tarutao National Park, Satun province, on Tuesday along with 71 people, including 65 members of Myanmar's persecuted Rohingya Muslim minority, Police Lieutenant-General Nawee Hemman told Efe news.
"We are now in the process of investigating whether they are illegal and during the investigation we continue to detain them," Nawee said.
A representative of Tarutao National Park, who wished to remain anonymous, said there were also five Myanmar crew members and one Thai captain found.
Of the 65 Rohingya Muslims, 31 were women and five were children.
It was not known if the group came from Bangladesh, where thousands of Rohingyas live in the largest refugee camp in the world after a Myanmar Army crackdown in August 2017 sent more than 725,000 fleeing from Rakhine state.
There have been many reports of Rohingyas attempting to leave Bangladesh by boat in recent months, presumably in order to reach Muslim-majority Malaysia.
Myanmar refuses to recognize the Rohingya as an indigenous ethnic group and refers to them instead as "Bengalis" who immigrated from Bangladesh.
In 2015, boats loaded with thousands of Rohingyas and Bangladeshis bound for Malaysia and Thailand were refused landing by authorities and left to drift in the Bay of Bengal and Andaman Sea.
Later, Malaysia and Indonesia offered shelter to 7,000 of the refugees and migrants.
( With inputs from IANS )