Chinese scientists have been preparing for a Third World War fought with biological and genetic weapons including coronavirus for the last six years, according to a document obtained by US investigators.

Evidence that Beijing considered the military potential of SARS coronaviruses from 2015 raised fresh fears over the cause of Covid-19.

The dossier by People's Liberation Army scientists and health officials examined the manipulation of diseases to make weapons 'in a way never seen before'.

MP Tom Tugendhat, chairman of the foreign affairs committee, said: 'This document raises major concerns about the ambitions of some of those who advise the top party leadership. Even under the tightest controls these weapons are dangerous.'

Chemical weapons expert Hamish de Bretton-Gordon said: 'China has thwarted all attempts to regulate and police its laboratories where such experimentation may have taken place.' The revelation from the book What Really Happened in Wuhan was reported yesterday in The Australian.

The document, New Species of Man-Made Viruses as Genetic Bioweapons, says: 'The new-found ability to freeze-dry micro-organisms has made it possible to store biological agents and aerosolise them during attacks.' It has 18 authors who were working at 'high-risk' labs, analysts say.

Intelligence agencies suspect Covid-19 may be the result of an inadvertent Wuhan lab leak. But as yet there is no evidence to suggest it was intentionally released.