The son of Vladimir Pasechnik (pictured) claims he was assassinated by Moscow

The son of a Russian defector who died in dubious circumstances in Wiltshire 17 years ago today broke his silence to claim his father was bumped off by Moscow.

Vladimir Pasechnik was a Soviet micro-biologist who defected to Britain in 1989 when he warned that Russia's germ warfare programme was 10 times greater than thought.

He went on to work at the microbiological research centre at Porton Down, near Salisbury, Wiltshire, and died in 2001 aged 64.

While Pasechnik's official cause of death was given as a stroke, his son, Nikita, suspected foul play and espionage activities were behind it.

And following the apparent poisoning of Russian spy Sergei Skripal and his daughter Yulia in Salisbury last Sunday, Mr Pasechnik is even more certain.

Despite voicing concerns that speaking out might put his own life in danger, the 53-year-old said he is in 'no doubt' that Mr Skripal was targeted by the Russian authorities - like his own father.

While Pasechnik's official cause of death was given as a stroke, his son, Nikita (pictured), suspected foul play and espionage activities were behind it

Mr Pasechnik, who lives in Bridport, Dorset, and works as an IT specialist, said: 'I have never done interviews before but I believe it is time to stop Putin so I need to say something.

'Putin is trying to avenge his opponents, to show his power and show what will happen to those who betray the system.

'In my opinion there is no doubt this man (Skripal) was poisoned by the FSB (the Federal Security Service for Russia) or another specialist force of modern Russia.

'The Russian authorities are very dangerous, they are killing people and they feel absolutely free to do that in the UK.

'They are very arrogant and they believe they can threaten anybody.'

Mr Pasechnik, who followed his late father to Britain in 1997, believes the Russian authorities were involved in his father's death.

He said: 'My father was always scared and told me they might kill him.

'He understood how serious the threat to him was.

'Officially his cause of death was a stroke but I spoke to doctors and they said his brain was severely damaged and they had never seen a stroke like it.

'I spoke to specialists in different countries and they said certain chemical substances could cause a stroke.

Pasechnik (pictured in 1979) was a Soviet micro-biologist who defected to Britain in 1989 when he warned that Russia's germ warfare programme was 10 times greater than thought

'I see similarities between my father and what has happened in Salisbury.

'My father was at home and he had a severe headache and felt dizzy.

'He tried to drive to his office and turned back then smashed his side mirror driving onto the garage before collapsing in the home.

'My step-mother was there and they rushed him to hospital but he died several weeks later.

'There was never a proper investigation into his death but perhaps it is too late now.

'What happened to my father has happened to many Russians who opposed Putin like Litvenenko, Berezovsky and the opposition leader shot in the centre of Moscow.

Russian spy Sergei Skripal (left) and his daughter Yulia (right) are fighting for their lives after being exposed to an unknown substance

'I fear Putin myself but I have to speak out because he must be stopped.'

He went on: : 'My father ruined the whole industry of biological weapons in Russia when he escaped to the UK and told the government and Margaret Thatcher (about Russia's programme).

'She told Gorbachev that Russia, despite the Helsinki convention, was still developing deadly weapons.

'This is the reason the Russian special forces - the KGB/FSB - wanted to kill him.

'There was a decision made within the KGB/FSB to kill my father.

'He was afraid of this and told me several times the story of the Bulgarian diplomat who was killed by an umbrella.

'It was a very difficult decision for my father to make the escape because he thought he would be tortured and imprisoned for life in the West but for him that was better than being a military criminal.