"It's complete drivel, rubbish, nonsense that somebody in Russian Federation would allow themselves to do such a thing ahead of elections and the World Cup", Putin told supporters Sunday after winning a fourth term as president.
"As a whole, of course, I think any sensible person would understand that it would be rubbish, drivel, nonsense, for Russian Federation to embark on such an escapade on the eve of a presidential election".
He also added that Russian Federation does not have such weapons and is "ready to co=operate with Britain to investigate the spy's poisoning".
They have been invited by the United Kingdom to independently verify the nerve agent used and will take at least two weeks to produce results.
". We are ready to cooperate, we said that straight away, we are ready to take part in the necessary investigations, but for that there needs be a desire from the other side, and we don't see that yet".
Officials from the world's chemical weapons watchdog will arrive in Britain on Monday to investigate the samples used in the attack and the results should be known in about two weeks, Britain's foreign ministry said.
Mr Johnson will be in Brussels to brief European Union foreign ministers on the Salisbury situation on Monday before meeting NATO Secretary General Jens Stoltenberg.
President Vladimir Putin is expected to win a fourth term, amid widespread voter apathy.
Presidential election : Polls open in Moscow with Putin on track to victory
Who is Putin up against? Yugene Yarmakov, 23, who was voting for the first time, said there were too many "joke candidates". Around 97,000 polling stations have been opened across this vast country, according to the Central Election Commission.
A team from the Organisation for the Prohibition of Chemical Weapons (OPCW) will visit the military research base at Porton Down in Wiltshire.
He told ITV's Peston on Sunday: "We support exactly what the prime minister said and we condemn Russian Federation for this, condemn them".
Moscow's reaction to the incident "was not the response of a country that really believes itself to be innocent", Johnson said on the BBC's The Andrew Marr Show.
Mr Skripal, 66, and Yulia, 33, remain in critical conditions in hospital, while Detective Sergeant Nick Bailey, who was exposed to the Novichok nerve agent while responding to the incident, is no longer considered critical.
Asked by Mr Marr if he was suggesting Porton Down was responsible, he replied: 'I don't know, I don't have any evidence of anything having been used'.
He said these could include "defending ourselves against cyberattack, (and) looking at any economic measures that could be taken against Russians who corruptly obtained their wealth".
The spy dispute has sent U.K. -Russia relations to Cold War-levels of tension.
Opposition lawmakers are calling on the government to clamp down on the illicitly gained money of wealthy Russians in Britain.
Russia's ambassador in London, Alexander Yakovenko, called for "cooler heads", telling the Mail on Sunday that the dispute is "escalating dangerously and out of proportion".