Alexander Litvinenko may have been ready to testify about Russian mafia and Moscow links

Vladimir Putin critic Alexander Litvinenko may have been murdered because he was prepared to testify about alleged links between Moscow and the Russia mafia. Litvinenko, 44, died after drinking tea laced with polonium-210 at a hotel in London and subsequently died on 23 November 2006 from radiation poisoning.

On Thursday, 21 January, Sir Robert Owen will set out the results of a six-month inquiry into the death of the former Russian Federal Security Service (FSB) spy. Owen's findings are set to increase tensions between the UK and Moscow.

A Spanish source was cited by The Times said that Litvinenko was prepared to claim that there were links between President Vladimir Putin's administration and Gennadios Petrov – the alleged boss of a Russian crime syndicate. The source said that former Russian Defence Minister Anatoly Serdyukov, and Viktor Zubkov, the Russian prime minister from 2007-2008, were named as being "subordinates" to the alleged head of the Tambovskaya-Malyshevkaya crime gang.

Spanish authorities were at the time attempting to bring down a contingent of the Russian mafia who were believed to have laundered profits from criminal enterprises in property and other means. Litvinenko was said to have given four hours of testimony in Madrid five months before his death which also is said to have included details that Putin had known of heroin trafficking from Afghanistan to Russia, but was not directly implicated.

The source told the newspaper: "It is our opinion that if ministers in [Putin's] government were subordinates to a criminal like Petrov, he [Putin] would have had knowledge of the link between government and criminal activity."

Russia has denied any involvement in the poisoning of Litvinenko with the radioactive isotope – the only known example of this type of assassination anywhere in the world. During the inquiry, it was heard that suspects Andrey Lugovoy and Dmitry Kovtun allegedly tried to kill Litvinenko twice.

The first dose was said to have been insufficient to kill the defected spy, who believed he was suffering from food poisoning. And on the second occasion, it was said that Lugovoy and Kovtun failed to acknowledge that the radioactivity left a trail through London like "the breadcrumbs left by Hansel and Gretel" and readings inside Lugovoy's hotel room were "off the scale".

His widow, Marina Litvinenko, said that if it is proved that Moscow ordered the killing, Russia should face sanctions. She told the Telegraph: "If proved, particularly in an official way in a court, you definitely need to react after the event.

"When talking about sanctions we are talking about a very serious moment because Russia is already under sanctions and it is just the ordinary people who suffer. These people (senior figures) definitely need to be under these sanctions.

"They still survive. They are able to travel. I think there should be a very serious discussion about what kind of sanctions and against whom."

Litvinenko claimed asylum in the UK in 2000 after trying to expose alleged corruption within the FSB – the successor agency to the feared KGB. He was said to have been prepared to appear as a witness at a trial of organised crime leaders, despite his identity being revealed.