MOSCOW -- Russian prosecutors said Monday that Britain's accusations over the poisoning of an ex-spy in England are in keeping with its behaviour in previous high-profile cases.

Britain has blamed Russia for the March 4 poisoning of former double agent Sergei Skripal and his adult daughter, Yulia. Russia fiercely denies the allegations.

Deputy Prosecutor General Saak Karapetian said Monday that the British government's refusal to share evidence echoes the 2006 death in London of ex-KGB officer Alexander Litvinenko, who was poisoned with radioactive polonium.

Russia rejected the verdict of a British inquiry that Russian security services killed Litvinenko and accused Britain of manipulating evidence.

Karapetian also cited the death inquiry for Russian tycoon Boris Berezovsky. Berezovsky died in Britain in 2013, and a coroner concluded it was impossible to say whether it was suicide or a slaying.

Berezovsky's death in 2013 could have been convenient for British authorities as the tycoon, who had co-operated with British intelligence agencies, was pondering the possibility of returning to Russia, the deputy prosecutor general said.

"British authorities are waging the anti-Russian campaign over the poisoning of Sergei Skripal and his daughter following the same scenario," Karapetian said. "In all those cases, people who faced Russian criminal charges were used as targets...helping create a semblance of motive for their physical elimination."

He added that the refusal by British officials to co-operate with Russia or publicly share any evidence in their secret probes was "excluding any possibility of their objective assessment."

In a show of solidarity with London, over two dozen Western allies have expelled more than 150 Russian diplomats. Moscow responded by ordering out the same number of Western envoys. Such mass expulsions were unseen even at the height of the Cold War.

Russian Foreign Minister Sergey Lavrov met Monday with the expelled Russian diplomats, denouncing the Western action as the "unprecedented provocation."

"We will never bend under ultimatums. It's not the language that they can use with Russia," Lavrov said.