Police discovered the group, which included 78 men, 60 women and 82 children, on Wednesday at a secluded jungle camp behind rubber plantations in southern Songkhla province.
"From what we see, they are likely Uighurs but we cannot confirm that until the identification process is completed," Pol Lt Gen Pharnu Kerdlarpphon, the chief of the Immigration Bureau.
Authorities initially said they believed the group was Turkish, because they claimed to be from Turkey. Chinese and Turkish diplomats have visited the people, who so far have refused to speak with the Chinese official, said Pol Lt Gen Pharnu.
"After we know their nationalities, we will press charges against them on illegal entry and push for deportation," he said.
The Turkik-speaking Muslim Uighurs originate from China's western region of Xinjiang, home to a simmering insurgency by the native Uighurs against what they see as discrimination and religious suppression by China's majority Han people.
The Beijing government has responded with a crackdown on what it calls terrorism incited by separatists who are influenced by radical Islam. Last year, clashes between authorities and members of the minority group left scores dead, including 40 police officers.
The US State Department urged Thailand to protect the group, which it identified as Uighurs.
"We are concerned about Uighurs generally (and) welcome reports that these Uighurs were rescued," State Department spokeswoman Marie Harf said on Friday in Washington, without directly addressing the possibility of the group's repatriation to China.
"We're encouraging Thailand to make sure their humanitarian needs are met."
New York-based Human Rights Watch called on Thai authorities to ensure the group is not forced to return to China, which has intensified a crackdown on the ethnic minority.
"Thai authorities should realise that Uighurs forced back to China disappear into a black hole," said Brad Adams, the Asia director of Human Rights Watch, adding that Uighurs forcibly returned to China face credible threats of torture.
Thailand has long been a transit point and hub for human traffickers, mostly transporting ethnic Rohingya fleeing violence and persecution in neighboring Myanmar.
More than 800 beleaguered Rohingya were found in raids in Songkhla in January 2013 after they fled sectarian violence in western Myanmar that has killed hundreds of people and displaced some 100,000 more.