The exodus was reportedly caused by rumors of a possible crackdown on undocumented workers.
The Thai government insists there is no crackdown, and no need for mass departure.
"We don't have policies to arrest as has been widely reported," Colonel Winthai Suwaree, a spokesman for the Thai army, said. "I don't want us to get panicked. Initially, authorities will extend flexibilities and want to reassure that migrant workers can continue working as usual."
In Thailand, where the unemployment rate is a low point-nine percent, many foreigners work low-paying jobs that Thais don't want to do and can be vulnerable to police harassment and exploitation.
Despite assurances from Winthai that the government is not actively seeking to arrest undocumented workers, he advised "employers to make a list of their employees in case authorities want to examine if it's necessary."
Meanwhile, IOM noted that it continuing "to work closely with the UN Resident Coordinator's Office, WFP, UNICEF, Cambodian Red Cross, Samaritan Purse, Wold Vision as well as with Immigration authorities and local government authorities" to respond to the needs of the 170,000 migrants who have fled Thailand.