A Nobel laureate scientist who helped discover the secrets of DNA was investigated by MI5 as a suspected Soviet spy, according to secret files made public yesterday.

Maurice Wilkins, a professor, was awarded the prize in 1962 with Francis Crick and James Watson after they revealed the double helix structure of DNA, the molecule which carries the genetic “life code”.

Eleven years earlier, however, he came under suspicion as a possible traitor who helped betray the secrets of the atomic bomb to the Soviets.

During World War II, the New Zealand-born Mr Wilkins worked on the joint US-British Manhattan Project to build the atomic bomb.

In 1951, the FBI informed the British they had received a report through a “reliable informant” that an Australian scientist on the team had been “in close touch with Communist Party members in Brooklyn, New York, and through them with the highest Communist officials in the US”.

The scientist was said to have passed on everything he knew about the programme, including “the set-up in New Mexico” – a reference to the main development establishment at Los Alamos.

In response, MI5 set about investigating all the Australian and New Zealand scientists who worked on the project.

Prof. Wilkins – who was by then working at King’s College, London – was put under surveillance, with his mail opened and movements monitored.

But apart from a report from 1946 from a junior MI5 officer who said that he had been “extremely vehement” in speaking out in defence of the convicted atom spy Alan Nunn May, they quickly concluded there was no evidence against him and the investigation was dropped.

One informant told MI5 that if Prof. Wilkins had left wing sympathies in the past, there was little sign of them now.

“He comes to the college every morning with a copy of The Times, which he has apparently read on the journey,” the informant said.

“He is a caricature of a scientist in that he seems to be both incapable of dealing with ordinary human situations and apparently uninterested in them.”