STEPHEN HAWKING: The professor feared the Soviet Union was spying on him in the Cold War

Professor Hawking – who died in March  aged 76 – was worried he was being targeted by the Soviet Union during a trip to Moscow.

His fears were revealed by his former wife Jane in her book Travelling to Infinity.

She revealed pals warned them to “behave as though our hotel room was bugged”.

Hawking had previously visited Moscow in his youth, and even helped smuggle banned Bibles into Russia.

Jane – who was married for 30 years to Hawking – revealed the couple checked out their hotel room upon arriving “half expecting to uncover a microphone”.

Hawking and his wife believed the first floor of the hotel had been sealed off as a base for Soviet Union “listening devices”.

The lift in the five-star Rossiya Hotel bypassed the floor, which was feared to be crawling with spies.

Hawking and his wife made their trip to Moscow in 1973 – the height of the Cold War which brough the US and Soviet Union to the brink of nuclar armageddon.

The period of tension lasted until 1991, and chillingly UN chiefs have now warned the “Cold War is back with a vengeance”.

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Jane wrote: "On the flight between Warsaw and Moscow, we were warned to behave as though our hotel room were bugged, not just for our safety, but for all the colleagues we would meet."

The Hawkings also believed an elderly Soviet scientist who Hawking knew – called Dr Ivaneko – may have been a KGB agent.

Other younger Russian scientists who can were him were always trying to “evade him” and he had once “disappeared” without a trace during a conference in Switzerland.

Jane, now 73, described him as “mysteriously unpredictable” and he is feared to have been a Soviet assigned “minder”.

Hawking and his wife made their trip to Moscow in 1973 – the height of the Cold War.

Russians who met them at the hotel were “reluctant” to enter the hotel, fuelling fears something was not right.

Once returning to Cambridge, Jane said: “For several weeks after our return, we were unable to communicate freely in our own home for fears the walls might be listening to us.”

The trip brought home to the couple the “unwelcome legacy of Soviet oppression”.

Hawking died earlier this year following a long battle with motor neurone disease – which left him wheelchair bound and unable to speak.

He overcame his illness however after being given just two years to live back in 1953.

Renowned for his theories on the birth and end of the universe, he helped unravel the mysteries of space and time.

Before he died, Hawking wrote a paper predicting the end of the universe – explaining how everything will all fade to black.