Lord Mandelson said today it would be “suicidal” for China to use its role in the Hinkley Point C nuclear power plant to compromise the UK’s national security.
China's ambassador to the UK recently warned over relations between the two countries after Westminster pushed back its decision on the project.
There's speculation that the surprise delay was due to security concerns, particularly in relation to potential Chinese involvement in future UK sites earmarked for nuclear development.
Speaking on BBC Radio 4, former business secretary Mandelson, said: "Nobody would trust Chinese investment again ... nobody would want to do business with China again."
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He warned against a further delay to the UK government's decision on Hinkley beyond current expectations for the end of September, saying economic ties with China will become more important in a post-Brexit world.
"We are probably less relevant to China out of the European Union because we'd be unable to influence that huge blocs future trade policies ... so we're not in the happiest of positions,” he said.