Current Russian lawmaker and former FSB security agent Andrei Lugovoi also reaffirmed his innocence in the high-profile murder and said he would be hiring his own London investigators to find the real culprits.

“In March I gave witness testimony to a British court, which was accepted by that court,” he said, adding that his evidence had been collected by “English lawyers” who visited Moscow and passed on the material to the court.

“It not only dealt specifically with the Litvinenko affair, but also other circumstances,” Lugovoi said of the March meeting.

“The court has accepted” the testimony, he told the Interfax news agency.

Prominent Kremlin critic Litvinenko died after drinking tea laced with radioactive polonium in a high-scale London hotel in November 2006.

Lugovoi was one of the two Russian suspects who met Litvinenko at the hotel.

He at the time owned a successful security firm with reputed close government connections and with the help of the state media used the scandal to develop a tremendous following and a seat in Russia’s lower house of parliament.

Moscow’s refusal to extradite Lugovoi after the murder further complicated its relations with London and the two sides are only slowly regaining each other’s trust.

Before his death, Litvinenko was one of the more public critics of then president Vladimir Putin.

His last book accused Russian secret services of plotting a string of apartment block bombings that Putin used as a pretext for launching the 1999 war in Chechnya.