Saudi Arabia's new £390bn mega-city and the 21k people who've paid the worst price for it

's £390 billion vision to build a new "mega-city" in the desert has claimed the lives of more than 20,000 workers in the last eight years, an ITV report has claimed.

Migrant workers have allegedly been subject to gruelling conditions, gone without wages and suffered human rights abuses, an investigation by an undercover female journalist has found.

People told the broadcaster they felt "trapped like slaves" as they worked 16-hour days for two straight weeks on part of Saudi Arabia's Neom project.

The multi-billion-pound scheme is said to have a workforce of 140,000, charged with building a city that is being promoted as offering "enhanced livability" for its future residents.

Estimates put the project's total cost from £387bn ($500bn) to £1.16trillion ($1.5tn). This is not the scheme's first criticism over . Howeitat tribe members have been killed resisting evictions from the land, according to reports.

Middle East Eye has reported that workers have been getting just four hours of sleep as they have to take a three hour bus journey into the desert to reach construction sites.

A worker told the publication: "There is little time to rest. We get tired. We suffer from anxiety day and night." Another said: "We are treated like beggars."

Neom was launched in 2017 and is being built near the Red Sea, east of Egypt and south of Jordan. It's part of Saudi Arabia's bid to become a global tourism hotspot, spearheaded by Saudi Arabia's Prime Minister, Mohammed bin Salman.

The scheme is said to be named after the Saudi leader, with "neo" meaning new and "m" being the first letter of bin Salman's forename.

ITV's documentary, Kingdom Uncovered: Inside Saudi Arabia, alleges "dangerous" conditions and illegal practices behind some of the world's costliest construction projects.

The broadcaster claims that, since the launch of Saudi Arabia's Vision 2030 to diversify the country's economy, 21,000 workers from India, Bangladesh and Nepal have died.

Undercover footage shot by the documentary makers includes shocking claims from workers. One is reported to have told the programme-makers: "We don't get enough rest. This lack of sleep has caused many accidents. There have been many. Just last month, there were four or five cases."

Nicholas McGeehan from the human rights organisation FairSquare said: "The reality is workers all over Saudi Arabia are subject to deeply abusive and dangerous exploitation. The abuses are systematically happening across the country."

Anurag Devkota, a Nepali human rights lawyer, said: "Migrant workers come here for a better future for their families, but instead, we are getting dead bodies in wooden boxes."

Neom has been approached for comment. A spokesman for the company told ITV: "We require all contractors and subcontractors to comply with Neom's code of conduct, based on the laws of Saudi Arabia and the policies of the International Labour Organization, and they are subject to frequent inspections of their workers' living and working conditions."

Saudi Arabia's government didn't respond to the filmmakers' requests for comment. Express.co.uk has approached the kingdom's government via the country's embassy in London.

Kingdom Uncovered: Inside Saudi Arabia first aired on ITV1 on October 27 and is now available to view on ITVX.