LONDON: The espionage saga unravelled with the death of a former Russian spy could trigger a diplomatic dust-up with President Vladimir Putin reportedly expressing his anger at Britain’s failure to gag him in the final hours of his life.

British Foreign Secretary Margaret Beckett told her cabinet colleagues that the Russian government had “taken exception” to the defector’s deathbed letter accusing the Putin regime of his murder, a leading British newspaper claimed on Sunday.

Beckett, who spoke to her Russian counterpart before Thursday’s cabinet meeting, said the Russians had “seemingly failed to understand” that Alexander Litvinenko was under police supervision rather than in custody. Prime Minister Tony Blair concluded the cabinet meeting by saying “the most important issue” was likely to be Britain’s long-term relationship with Moscow, The Sunday Times said.

The Foreign Office officials confirmed the Russians had raised the issue of Litvinenko’s letter with Beckett and British diplomats, it said. Until now, the government has admitted only that the Russians had agreed to assist Scotland Yard with its inquiries.

Litvinenko, 43, a former KGB agent who was a fierce critic of Putin, died late last month after falling gravely ill from what doctors said was poisoning by the radioactive element polonium-210. In interviews before his death, Litvinenko claimed he was ordered to hire assassins to kill rivals to Kremlin-favoured business leaders and execute whistle-blowers who threatened to expose corruption.