London/Moscow - The widow of murdered Russian dissident Alexander Litvinenko was Sunday set to mark the second anniversary of his radioactive poisoning death amid prospects of a possible new development in police investigations, it was reported Sunday.

The Press Association, citing the Litvinenko Justice Foundation, said Marina Litvinenko was marking the occasion in private while British authorities were still considering her call for an inquest into her husband's murder.

"Mrs Litvinenko will mark the second anniversary of her husband's death privately, without public events or interviews," the foundation said.

The second anniversary of the November 23, 2006 death of the former KGB agent comes on a weekend when one of the prime suspects in the case, Andrei Lugovoy, has stated his readiness to travel to Britain for questioning by Scotland Yard.

In an interview with The Times on Saturday, Lugovoy spoke of going to Britain along with a further suspect in the case, Dmitri Kovtun, in order to clear their names - providing that they received guarantees against their arrest.

Litvinenko had died of radioactive polonium poisoning shortly after drinking tea during a meeting at a West End hotel with Lugovoy and Kovtun, both former KGB contacts.

British prosecutors consider the 42-year-old Lugovoy as the main suspect in Litvinenko's death.

In The Times interview conducted in Moscow, Lugovoy said "we have this idea for Dmitri to travel to London to talk to representatives of the prosecutors. We are looking for a way to achieve this if we could get guarantees from the Government of Great Britain."

He also did not rule out travelling to London later himself, but on condition that Kovtun is not extradited to Germany. Kovtun is under investigation after apparently leaving radiocative traces while visiting Hamburg before the London meeting with Litvinenko.

On his deathbed at the time, Litvinenko directly accused then- president Vladimir Putin of ordering his assassination.

In a throwback to the old Cold War era of intrigue and hostile suspicions, the Litvinenko case at the time triggered a period of angry exchanges between London and Moscow, which has refused to hand Lugovoy over to Scotland Yard.

Meanwhile the Litvinenko Justice Foundation expressed its disappointment at developments in the case.

"There has been no progress regarding the extradition to the UK of the prime suspect, Andrei Lugovoy, from the Russian Federation," said the foundation. "Mrs Litvinenko's appeal to the newly elected president, Dmitry Medvedev, calling on him to stop protecting Mr Lugovoy, had no response."

The foundation was established in March 2007 by Marina Litvinenko and two of the murdered man's friends, Boris Berezovsky and Alex Goldfarb. The group was later joined by prominent human rights lawyer Louise Christian.