The widow of poisoned former KGB agent Alexander Litvinenko denies that he was working for British intelligence as the man charged with killing him has claimed.

Andrei Lugovoi, a former KGB man sought on a murder charge in Britain, has said Litvinenko was working for MI6, the British foreign intelligence agency, and that British intelligence may have had a hand in the slaying.

“He will try everything to defend himself,” Marina Litvinenko said of Lugovoi in an interview with The Associated Press on Friday.

Marina Litvinenko is promoting a new book titled “Death of a Dissident,” which she co-authored with her husband’s friend Alex Goldfarb. She said her husband carried out intelligence work on behalf of British businesses, but not the foreign intelligence service.

British intelligence officials have also dismissed the allegations by Lugovoi that Litvinenko, a fierce critic of Russian President Vladimir Putin, worked for them.