The vast majority of Cambodian migrant workers to Thailand are continuing to use unofficial channels to enter the country, choosing not to use a passport or worker permit due to the high cost and long wait times, according to a survey released on Monday.

Tens of thousands of undocumented Cambodian workers were deported en masse from Thailand in 2014, but the survey – conducted by the International Organization for Migration – shows that two years later, almost 80 per cent of migrants still eschew documentation.

Only 22 per cent of respondents used a passport to process their job applications, with most preferring to use irregular channels to cross the border and register for non-Thai identity cards, bypassing the time-consuming approval needed by the Cambodian Embassy.

“Thus, there is no incentive to stay in Cambodia to go through legal recruitment under the current MoU [memorandum of understanding] process for Cambodian workers to migrate to Thailand,” the report reads.

The IOM surveyed over 600 workers who have returned to Cambodia since Thailand’s military junta took power in 2014.

However, leaving Cambodia through unofficial channels had its drawbacks, the survey found. Of the 19.5 per cent of workers who faced abuse or bad working and living conditions in Thailand, an overwhelming 80 per cent were undocumented.

The survey also showed that a lack of job prospects, low salaries and financial debt were the main drivers for immigration to Thailand, with the high costs attached to acquiring documents being the top reason for workers lacking a passport or identification card.

Moeun Tola, head of labour rights NGO Central, said the crux of the issue was the government’s failure to provide employment opportunities to citizens combined with passport and visa formalities still being “too complicated”.

“So for those who are undocumented, the employers don’t pay them the minimum wage or overtime and threaten workers with deportation if they object,” he added.

Workers with proper documentation, on average, received close to the minimum wage of 300 baht (a little under $10) a day, whereas those without documents got about $5.70, according to Tola.

Andy Hall, an international affairs adviser at the Thailand-based Migrant Rights Network, said the inflow of undocumented workers was a major problem, and agreed with the report’s finding that certain sectors were worse than others.

But, he added, the potential for abuse “is a risk factor, even for the ones who come through legal channels”.

Top Neth, a spokesman for the Interior Ministry’s identification department, conceded that the cost of a passport was high in Cambodia, close to $115, but said workers could use a worker’s travel document, which was much cheaper.