In a private room of a London hospital, the spy who knew too much was slowly dying. The once fine features of Alexander Litvinenko were pale and drawn. Barely a month earlier he had been a fit man who often ran five miles a day; now, unable even to eat, he was being kept alive by the intravenous drip in his arm.

His hair had fallen out. He had lost two stone. He was unrecognisable as a former lieutenant colonel of the FSB, the Russian secret service, who had fled to London after making an enemy of Vladimir Putin, the Russian president.

Now his immune system was shot to pieces, his white blood cells destroyed. His vital organs, including his liver and kidneys, were beginning to fail. He was showing all the signs of being poisoned by a radioactive substance.

Next to the bed his wife Marina, an attractive blonde of 44, sat trying to hold back her tears. Visitors had to wear plastic gloves and other paraphernalia to prevent infection.

Inside the racked body of Litvinenko bitterness burnt alongside the poison. He had not yet given up his fight. In an interview with The Sunday Times before this newspaper broke the story last weekend, he claimed he was the victim of a plot by his enemies in Russia.

“There is a special unit within the FSB on poisoning and developing poisons,” he said, his voice faltering. “I know they are using poisons in Chechnya. The service are putting special emphasis on this.”

He paused, reached for a plastic bowl on his lap and vomited. When he had recovered he continued: “Everything that is happening is fitting very neatly a particular logical chain. First, the Russian parliament passes a law in the middle of this year which allows the government, allows the president, to pursue and attack ‘extremists’ all over the world. So now it’s legal.

“Then a few days later they enacted another [law] which defines ‘extremist’. Anybody who is critical of the government falls under these broad definitions.”

Few had been more vitriolic and outrageous in their criticism of Putin and the Kremlin than Litvinenko.

“This unties the hands of the secret service because nobody can now say it’s illegal under Russian law.”

He vomited again and a nurse came into the room. Litvinenko tried to wave her away, but she told him it was time for his next dose of antibiotics and he quietly complied. Then he continued.

“I know what’s happening within the [Russian spy] service. Once a law like this is enacted the services immediately start planning activity, frantic activity, setting up new units that would implement the new initiative. The services consider it as an order actually.