The UK is expected to ask Moscow to extradite two Russian nationals suspected of killing one person and critically injuring three others by poisoning them with a nerve agent, Britain's Guardian paper has reported.
The Times newspaper alleged in reports that detectives from the Metropolitan Police in London are understood to be confident they have identified the would-be assassins who used a perfume bottle containing the deadly poison novichok in their unsuccessful attempt to kill Sergei Skripal and his daughter Yulia, aged 33, in March.
Any extradition request is likely to be rejected by Russian Federation - and risks inflaming diplomatic tensions between London and Moscow, which are the worst since the Cold War.
Now, Russia has called reports of extradition requests bogus. "It's nearly a rerun of the situation", The Guardian quoted a government source as saying. "The police have managed to identify the people coming over and going back again", a Whitehall source said.More news: Trump promises to stay the course on tariffs
While the request is nearly certain to be rejected out of hand by the Russian authorities, it will likely reignite the bitter diplomatic row which erupted following the poisoning of former Russian spy Sergei Skripal and his daughter, Yulia, in March.
They were found in a serious condition on a bench in The Maltings shopping centre, and the discovery of the substance sparked a city-wide investigation with police having to cordon off large areas, including where they had eaten dinner that evening.
In 2007, President Vladimir Putin rejected an extradition request for two Russians suspected of the assassination of the former FSB officer Alexander Litvinenko in London using radioactive polonium.
Following this, Charlie Rowley and Dawn Strugess were treated for exposure to the nerve agent. She died eight days later, but he has since been released from hospital. Mr Rowley recovered but Ms Sturgess died last month.