Labour inspectors have confirmed to the AD that they have carried out checks on working conditions at the American embassy building under construction in Wassenaar and that an investigation is underway.

‘We are looking into if one or more of the four laws which we are responsible for monitoring have been broken. These include the law on working hours and the law on employing foreigners,’ spokesman Paul van der Burg told the paper.

The AD says it has been told by two whistle-blowers that workers are being forced to work overtime on a structural basis and that foreign workers are being used whose paperwork is not in order.

‘Nobody dares to speak out,’ one is quoted as saying. ‘Earlier this year two workers who stood up for their rights were sacked on the spot and removed from the Netherlands.’

The paper says most of the 250 construction workers are ‘foreign’, mainly Romanian, Turkish and Bulgarian nationals and some have been brought into the Netherlands under the highly-skilled migrants scheme.

An embassy spokesman told DutchNews.nl: ‘The US embassy is aware of these allegations and the US government will continue to cooperate to ensure full compliance with Dutch law.

‘The US government complies with all local labour laws, including those protecting the rights of workers, and requires our contractors to do the same.   As is normal with projects of this scale, [the ministry] regularly reviews compliance with Dutch regulations.  We have not been made aware of any findings of irregularities under Dutch labour laws.’