The father of Alexander Litvinenko, the Russian spy turned Kremlin opponent who died from polonium poisoning in London in 2006, has called his son a "traitor" and begged Russia for forgiveness so he can return home.

Valter Litvinenko fled to Italy with his family in 2008, apparently to avoid retribution from Russian authorities after accusing the Russian government of ordering his son's assassination. But in a interview broadcast on Russian state television yesterday, the 73-year-old broke down into tears and begged to be allowed to return to Russia.

"Forgive me, my motherland. And help me return home, help an old man," he said. On camera, the father of the murdered KGB agent described a miserable existence in poverty, living in an unheated flat in a small Italian town. His wife, Alexander's mother, died last year.

Valter Litvinenko has been a vocal critic of the Russian government, but he says that opponents of the Kremlin, such as London-based exile Boris Berezovsky, are now ignoring his calls and have no desire to help him.

Alexander Litvinenko's widow Marina recently said her husband had co-operated with British security services, and was paid for his work. In the interview, Mr Litvinenko's father says this revelation changed his view of his son's death.

"What am I supposed to do, cry out around the world about my traitor of a son?" he says. "When I found out he had worked for their spy agencies... that was a real blow. That's it. It was such a blow."

Excerpts of the interview were accompanied by a voiceover stating that the television station received a letter from Valter Litvinenko a few days ago, calling his son a "British spy" and asking for forgiveness. The report chastised Mr Litvinenko's past statements, saying "many in the West" have used his accusations to their advantage.

British authorities believe that Alexander Litvinenko was murdered by Andrei Lugovoi, another former KGB agent, at a meeting in a London hotel.

From his deathbed, the Russian defector accused Prime Minister Vladimir Putin, then the president and himself a former KGB agent, of ordering the murder. Russian authorities have denied being behind the killing, and have refused to extradite Mr Lugovoi.

He now enjoys extra protection as a Russian MP, after he was elected to parliament on the ticket of a nationalist party with links to the Kremlin.

The recanting of Alexander Litvinenko's father appears to be borne as much out of material concerns as ideological ones. Russian television found him in a small, freezing apartment.

"It's cold here, and nobody needs you. You die, they'll just pull your body out and take it away. Like with my wife, she also always wanted to go home, back to Russia," he said.

It was unclear last night whether Russia would offer Mr Litvinenko help to return to Russia, but the tone of the report suggests the Russian authorities intend to extract as much political capital as possible from Valter Litvinenko's recantation.

It is another propaganda coup for Russia just weeks after Jonathan Powell, Tony Blair's former chief of staff, admitted that a fake rock in a Moscow park, that Russia said in 2006 was used by MI6 to transmit and receive information, was indeed used by British spies.

The admission, made as part of a BBC documentary series about Vladimir Putin, prompted pro-Kremlin figures to lambast Russia's liberal opposition, many of whom suggested that the "rock scandal" was a cheap trick manufactured by Russian security services.