The Japanese government has been accused of a cover-up after it refused to allow independent testing of water from the Fukushima power plant that is likely to be released into the Pacific Ocean.

Officials at the industry ministry on Monday said the water stored at the crippled nuclear site was "safe" to release into the Pacific Ocean, despite concerns about radioactive material from environmental and citizens' groups.

Following a recent visit to the plant, the Tokyo Electric Power Co (Tepco) told The Telegraph that concerns over security prevented independent testing.

"Other organisations are not permitted to carry out tests of the water”, Hideki Yagi, a spokesman for Tepco, told The Telegraph.

“If we are going to allow external organisations to test the treated water then we would need to go through very strict procedures and due process because that water is contaminated. If it is taken outside this facility, then there need to be strict regulations”.

Both Greenpeace and the Citizens’ Nuclear Information Centre (Cnic), an anti-nuclear lobbying group, suggested that Tepco may be trying to cover up the true scale of contamination of water stores at the site.

Shaun Burnie, senior nuclear specialist for Greenpeace, says the refusal to permit third-party testing only serves to raise new concerns about plans to discharge the water into the ocean.