Former Superintendent Malcolm Baker said his colleagues endured “a very tense three or four days” before being re-examined and given the all clear.
He also revealed health professionals working with Scotland Yard were stopped from publishing a paper in medical journal The Lancet because detectives feared it would alert the Russians to how they solved the case.
A Channel Four investigation, to be screened tomorrow, will claim officers who travelled to Moscow in search of evidence were frustrated by a campaign of dirty tricks.
Police investigating Alexander Litvinenko’s murder were wrongly told they might develop cancer
Mr Litvinenko, a former KGB agent-turned-whistleblower, was killed in 2006 after polonium-210 was slipped into his tea, allegedly by Andrei Lugovoy and Dimitri Kovtun on the orders of Vladimir Putin.
A small number of people, including police officers, were informed they had been contaminated and a consequence of that was they had an increased chance of suffering from cancer
Malcolm Baker – Former Superintendent
Mr Baker said that those who had been in close contact with Mr Litvinenko, including his family, police and medics, gave urine samples to check if they had been contaminated.
He said: “In the early period of that testing, probably because of the intense activity and tiredness, mistakes were made and some decimal points ended up in the wrong place.
“As a result a small number of people, including police officers, were informed they had been contaminated and a consequence of that was they had an increased chance of suffering from cancer.
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‘Mistakes were made and some decimal points ended up in the wrong place’, said Baker
“They had a very tense three or four days but when the calculations were re-checked they were told they didn’t need to worry.
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“You have to remember this case was unprecedented. Even the textbooks that were referred to originally for case studies proved to be wrong.”
Detectives initially picked up traces of polonium at a sushi bar in Piccadilly where Mr Litvinenko had met with Mario Scaramella, an Italian security consultant, shortly before falling ill.
The radioactive trail revealed more than 40 contaminated locations across London.
Mr Litvinenko was killed in 2006 after polonium-210 was slipped into his tea Shocking photographs depict the horrors of Bioterrorism Mon, February 20, 2017
Bill Gates warns genetically engineered viruses will wipe out hundreds of millions.
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Gas used to be released directly from cylinders, but this method was replaced by shells in 1916.
Police eventually found the source at the Millennium Hotel where Mr Litvinenko had met former KGB agents Lugovoy and Kovtun on November 1, 2006.
A test of the hotel’s crockery found a teapot with off-the-charts reading for polonium-210.
Officers then discovered both men had met Mr Litvinenko two weeks earlier at the Itsu restaurant.
Hunting The KGB Killers is on Channel 4 tomorrow at 9pm