The foreign workers are taking flight for fear of being arrested by Thai authorities following rumours that the military is preparing to launch a massive crackdown on illegal migrants, according to local media.
Patamaporn Rattanadilok Na Phuket, a spokeswoman for the National Council for Peace and Order (NCPO), said on Saturday no crackdown on foreign workers had been ordered.
But she admitted that because of the rumours, some businesses were concerned and sent the foreign workers back home.
Also, she said the harvest season had also begun, prompting some to return home to help their families.
Large numbers of irregular migrant workers from Cambodia are leaving Thailand through the Poi Pet border checkpoint, according to IOM, which has deployed staff on the border.
Many are effectively stranded, with no money to pay for onward transport to reunite with their families, according to an IOM report on Wednesday.
IOM is an inter-governmental organisation with 155 member states, a further 11 states holding observer status and offices in more than 100 countries.
IOM's Cambodia office has sent three buses to help transport the returnees, but is concerned that flows have suddenly increased, placing a strain on services at the main border crossing.
“There are usually only about 100 migrants coming through each day,” said Leul Mekonnen, IOM’s acting chief of mission in Cambodia. “But we are already seeing more than 1,000 a day and we do not know what the coming days hold.”
IOM Cambodia is working closely with Cambodian immigration officers at the Poi Pet Immigration Centre at the request of the Department of Immigration to assist the migrants with onward transport to their provinces.
More than half of the migrants are women and children. Aside from transport, there is also a growing need for food, water, health care and shelter. IOM currently is assessing needs and looking for emergency funding to deal with the sudden influx.
“IOM’s primary concern now is the safety and dignity of vulnerable migrants,” said Mr Mekonnen. “We are doing our best to get them home as soon as possible.”
The Chinese news service Xinhua reported on Friday that Cambodian Prime Minister Hun Sen had ordered 150 military trucks to transport migrant workers back to their home provinces.
On Wednesday, Koy Kuong, a spokesman for the Cambodian Ministry of Foreign Affairs, said the massive deportation was due to the Thai military coup, which forced factories and enterprises to stop using illegal migrant workers, according to Xinhua.
He also dismissed news reports that the Thai military had shot Cambodian workers.
Pol Lt Col Benjapol Rodsawat, deputy chief of Sa Kaeo immigration police, told MCOT that local Thai officials had tried to explain to Cambodian workers that they should not be afraid if they work in Thailand legally, saying the Aranyaprathet checkpoint would never be closed.
A number of Thai companies would suffer a shortage of workers following the returning home of the Cambodian workers, Pravit Khiengpol, director general of Thai Labour Ministry’s Employment Department, told MCOT.
Official statistics show that a total of 441,569 Cambodian workers have registered with the Employment Department.