BRITAIN is set to demand that Russia hands over two suspects they believe were behind the Salisbury Novichok attacks.

Re-opening the furious row over the failed poisonings, the Government will ask Moscow extradite two Russians who left one dead and three injured in the nerve agent attack earlier this year.

Police have finally pieced together enough evidence to pinpoint who was responsible for the attacks, The Guardian reported.

They have been tracking their movements for months, since ex-Russian spy Sergei Skripal, 67, and his daughter Yulia, 33 were severely injured in a poison attack in March - and found slumped on a bench in Salisbury.

Months later Dawn Sturgess died after coming into contact with what was thought to be the same batch of nerve agent in Amesbury - handed to her in the form of a perfume bottle - but her boyfriend Charlie Rowley survived.

The UK has formally pointed the finger at Russia for being behind it, but Vladimir Putin's country has denied any involvement.

Sources told the newspaper that the Crown Prosecution Service is ready to file the request.

Officials have been rowing about whether it's worth bothering - when Mr Putin is likely to refuse the request, opening up the whole row again.

Mr Putin denied a similar request for two Russians who were suspected of being being the 2006 assassination of the former FSB officer Alexander Litvenenko in London.

Britain has also blocked extradition requests from Russia too. In 2003 Tony Blair said Boris Berezovsky was unlikely to get a fair trial - a decision that enraged the Russian leader.

The CPS tried for a decade to put Dmitry Kovtun and Andrei Lugovoi on trial, with no success.

Meanwhile, Mr Lugovi was made mayor and given a special honour in Russia.

The country's constitution forbids extradition of its citizens explicitly too.

Elena Tsirlina, a lawyer for Litvineko’s widow, Marina, said Russia’s response to the extradition request would be an expression of outrage.

"They will move to protect the suspects and cite article 61 of the Russian constitution, which prevents Russian citizens from being extradited to another country," she said.

She again called for a public inquiry into the Skripal poisonings.