Moscow (AFP) - President Vladimir Putin on Sunday rubbished claims that Russia poisoned a former spy in Britain, on the eve of international chemical weapons experts heading to the UK to probe the attack.
"It's complete drivel, rubbish, nonsense that somebody in Russia would allow themselves to do such a thing ahead of elections and the World Cup," Putin told supporters after winning a fourth term as president.
"We have destroyed all chemical weapons," he added, rejecting Britain's claim that only Moscow could be behind the nerve agent attack on former double agent Sergei Skripal and his daughter Yulia.
The poisoning in the English city of Salisbury on March 4 has led to a diplomatic crisis, with Britain expelling 23 Kremlin diplomats.
Technical experts from Organisation for the Prohibition of Chemical Weapons will visit Britain on Monday to collect samples of the nerve agent used in the attack.
"These will then be despatched to highly-reputable international laboratories selected by the OPCW for testing with results expected to take a minimum of two weeks," said a statement by Britain's Foreign Office.
Putin said Russia is "ready to take part in the investigation", although earlier on Sunday British Foreign Secretary Boris Johnson accused the Russians of "smug sarcasm and denial" in response to the accusations.
Moscow's "malign, disruptive behaviour" internationally was the reason why allies were "inclined not to give Russia the benefit of the doubt," he told BBC's Andrew Marr Show.
Johnson also said Britain would target wealth linked to the Kremlin as a further measure following the spy poisoning.
"Where people have obtained wealth by corruption and where we can see a link with the Kremlin, with Vladimir Putin, it may be possible to have unexplained wealth orders and other sanctions on those individuals," Johnson said.
Johnson said the government was considering something similar to the US "Magnitsky Act" which was adopted in 2012 to punish Russian officials accused of human rights violations.
The act imposed a visa ban and froze the assets of Russian officials implicated in the death of lawyer Sergei Magnitsky, a tax fraud whistleblower who died in Russian custody in 2009.
However, the minister faced awkward questions over a tennis match he played with the wife of former Kremlin minister Vladimir Chernukhin, in return for a £160,000 ($223,000, 181,500 euros) donation to his Conservative Party.
- Russia points at Porton Down -
On Saturday, Russia's ambassador to the European Union, Vladimir Chizhov, said Moscow "had nothing to do" with the attack, accusing Johnson of "acting in an inappropriate manner" by pointing the finger at Putin.
"Russia has stopped production of any chemical agents back in 1992," he told Marr, the day after Moscow expelled 23 British diplomats in a tit-for-tat measure.
But the Foreign Office dismissed the claim, saying it had "information indicating that within the last decade, Russia has investigated ways of delivering nerve agents likely for assassination.
"And part of this programme has involved producing and stockpiling quantities of Novichok," a statement said.
Chizhov also appeared to suggest that Britain itself may have been the source of the chemical agent.
"When you have a nerve agent, you check it against certain samples you have in your laboratories," he said.
"And Porton Down, as we now all know, is the largest military facility in the UK that has been dealing with chemical weapons research -- and it's actually only eight miles from Salisbury."
Johnson called the accusation "satirical", adding it was "not the response of a country that really believes itself it to be innocent."