Walt Disney Co has become the latest big corporate to come under the firing line over the work conditions laid out by its contract suppliers. Two labour groups have criticised the company over the harsh conditions that some of the park workers are forced to work under.

Students & Scholars Against Corporate Misbehaviour, a Hong Kong-based advocacy group, claims that some workers at eight of Walt Disney's suppliers it had looked into, were forced to work long hours. Some of them even worked 144 hours of overtime per month. They were also paid wages below the legal minimum.

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That was not all. The group claims that injury levels at these factories were high, because of the old machinery in use and the lack of training or protective equipment supplied to the workers. The report is based on investigations conducted from July 2015 to February 2016.

China Labor Watch, in a separate report titled The Dark World of Disney, raised work conditions at two other factories. This included low wages, exposure to chemicals and the ineffective audits of working conditions by the factory's clients.

Both groups said their investigations involved working undercover at these factories. They noted that their investigations only covered a fraction of Disney's total suppliers. Among others, these supplier companies often held back full overtime pay, fined workers for taking leave and often employed workers without an official contract.

People at China's first Disney
People walk past China's first Disney store at Pudong financial district in Shanghai. Reuters

The Hong Kong group also slammed Disney for its lax oversight of its supplier factories. It also noted that third-party inspections are flagged in advance. These factories made branded bags, hair clips and mugs, Reuters noted.

"Knowing the time and subject of the audit, the factories were able to hide things in advance and the genuine labour conditions could not be uncovered," the Hong-Kong based group said.

Walt Disney, which is opening its $5.5bn theme park in mainland China on Thursday (16 June) in Shanghai, has said that it would investigate any allegations taken against its suppliers. A Disney spokeswoman said, in an emailed statement to Reuters, that it takes "seriously claims of labour standards violations against the independent facilities producing Disney-branded products."

She continued: "It is our practice to thoroughly investigate those allegations and assist facilities in remediation efforts and comply with local regulations."