Safety issues specifically relevant to the potential site of a third nuclear power station on the Suffolk coast will be addressed in the run up to its construction, a national watchdog has made clear.

The Office for Nuclear Regulation (ONR) said its safety assessment of the design of the UK version of the European Pressurised Reactor – two of which could be built as part of proposals for Sizewell C – had been completed. However, issues specific to the Suffolk site would be addressed during the detailed design and construction stages.

The clarification follows a dispute between Suffolk Coastal MP Therese Coffey and Sizewell Stakeholder Group member and leading nuclear industry critic Pete Wilkinson over the state of progress in the resolution of safety issues.

Dr Coffey had told a public meeting at Yoxford that the ONR had completed its assessments of the design of the type of reactor planned for Sizewell C and had issued a formal design acceptance confirmation. But Mr Wilkinson, who lives in nearby Peasenhall, said he believed people attending the meeting had gained a mistaken impression that all safety issues had been resolved and Sizewell C was “inevitable”.

“Although ONR says the GDA has been completed, there are still a number of issues which have been identified as needing settlement at a future date,” he said.

“If an issue is found to be irresolvable ONR will have to withdraw authorisation.”

Dr Coffey said she had correctly described the situation. “The ONR issued a design acceptance confirmation of the reactor proposed to be used in December 2012,” she said. “The Environment Agency has also issued a statement of design acceptability.”

An ONR spokeswoman said the GDA would be used in any site specific design but that there would also be specific issues associated with each of these sites.

Before construction started a site licence will also have to be granted, enabling the ONR to constantly monitor activities during all stages, she added.