Badsha Md is trying to make sense of everything he has been through.

Ten days ago the building worker found himself in Singapore's Changi Airport with a repatriation agent determined to put him on a plane to Bangladesh.

Only intervention by a volunteer from a migrant rights organisation kept him in the island nation.

"I still don't know why my boss wanted to send me back," he told ABC News.

Singapore is developing at a relentless pace, and construction work is seen as dirty and low on the social scale.

There is a dearth of citizens willing to take it on, so Singapore imports the workers.

There are more than 300,000 men like Badsha, from Bangladesh, India, Myanmar, and China, who build malls, train lines, roads, and skyscrapers.

While many see Singapore as a land of opportunity, migrant construction workers earn very low wages relative to the permanent population.

With their work permits tied to specific employers, they are also vulnerable to exploitation.

One of their biggest fears is "the gangster".

'The gangster was very angry, he was shouting'

Migrant workers ABC News spoke to referred to "gangsters" as the men who would forcibly send them home.

One worker described being woken up and told to pack his things immediately.

For men who have paid up to $S10,000 (AUD $9,973) in agents' fees to secure employment in Singapore — the threat of being forced home is frightening.

"Employers don't use repatriation on a daily basis," Charan Bal, a researcher at Binus University in Jakarta, said.

"Typically they use repatriation threats, and then forced repatriation, to resolve employment disputes over wages, working conditions and work injuries. It's really an employer strategy to resolve employment disputes in their favour."

Badsha was driving a forklift when he hit a large hole in the road, jolting him heavily and leaving him with a pain in his back.

He said he had also not been fully paid.

"My boss said he would take me to the doctor the day after the accident, but he didn't," Badsha said.

"On the third day, I was asked to go to the office. Then in the afternoon the gangsters came."

Bangladeshi migrant worker Badsha Md, who did not want to be identified, waits to file a complaint following an attempt to forcibly repatriate him. ( Supplied: Tom White )

Badsha was then asked to sign papers he did not understand.

"The gangster was very angry, he was shouting. That's why I signed," he said.

The documents were in English — a language Badsha speaks with difficulty.

After signing, he was taken to his dorm, then to the repatriation agency until it was time to go to the airport.

While still at the agency, Badsha rang his brother, who then called the Humanitarian Organisation for Migration Economics (HOME).

Volunteer Kokila Annamalai headed to the airport to intercept the forced deportation.

"I tell Badsha 'it's time to go'," she wrote in an account on HOME's website.

"We start pushing the trolley with his luggage on it and the repatriation agent loses it.

"He physically restrains us, stops the trolley with his foot and shoves Badsha, grabbing his shoulder to hold him back, all this while trying to talk to the police on the phone."

Workers make false allegations to prolong their stay: UTR

The agent was from UTR Services, one of Singapore's established repatriation companies.

UTR's director, J Ravinthiran, who has been involved in this work since the late 1990s, rejected HOME's complaints.

He said Badsha had not been confined or held against his will.

He also claimed it is common for workers to make false allegations to prolong their stay in Singapore.

"Most of the companies use us to facilitate repatriation, because maybe they don't have the manpower or expertise to do it. There's nothing like needing to force the worker, or that we are so special we can make him go back," he said.

The company charges $S300 per man for their services.

If the job is called off when a worker is intercepted or tells authorities at the airport that he does not want to travel, UTR charges $S100 to $S150.

UTR Services director J Ravinthiran explains documents to a migrant worker about to be sent back to Bangladesh by his employer. ( Supplied: Tom White )

According to Mr Ravinthiran, UTR repatriates 50 to 60 migrant workers each month.

That is a drop from the late 1990s — when he said he would repatriate up to 600 men a month.

"Today the workers know their rights," he said.

Repatriation services unregulated

Repatriation services remain unregulated in Singapore.

The Ministry of Manpower does occasionally investigate allegations of violence or illegal confinement.

"Even in the Parliament, now they don't have an idea," Mr Ravinthiran said.

"But we ourselves put in a request, it's good if you could regulate repatriation, what can be done, what cannot be done."

ABC News contacted the Ministry of Manpower for comment, but no response was provided.

Badsha now has a medical certificate from a doctor as proof of his back injury. He has also lodged a complaint with the Ministry and remains in Singapore pending an investigation.

There is no indication how long that will take, so Badsha waits, unable to work until his back heals.

"I don't know what to do," he said. "I can only wait and see."