The nuclear watchdog, which oversees sites across the country and has only recently become independent from the national health regulator, has been consulting with engineering giants such as the US Jacobs Group and the UK’s Amec, among others, the report said.

Should the regulator implement biased advice from companies with interests in the industry and the UK, it could put all of the country's reactors in danger, critics say.

In April, ONR signed a five-year deal with Jacobs, which is involved in the construction of the Trident nuclear defense deterrent, to receive help in assessing external hazards, decontamination of existing nuclear sites and future reactor designs, according to the paper.

Amec, which looks after a nuclear reprocessing site on the Irish Sea, advises on reactor chemistry and radiation protection. The Arup consultancy and construction firm Sir Robert McAlpine, which together have worked on more than a dozen British nuclear plants, help with civil engineering issues.

The ONR representatives said the advisers were never the same people as potential licensees, but professionals in the area too few to be readily found outside of the nuclear companies.