The two suspects in the poisoning of ex-Russian spy Sergei Skripal and his daughter are civilians, not criminals, Russian President Vladimir Putin says.
The UK government had named them as Alexander Petrov and Ruslan Boshirov, and said they were from Russia's military intelligence service, the GRU.
Mr Putin said he hoped the men would tell their story soon.
Downing Street said that Russia has repeatedly been asked to account for what happened in Salisbury.
The prime minister's official spokesman said that Moscow "had replied with obfuscation and lies".
"I have seen nothing to suggest that has changed," the spokesman said.
Meanwhile, Security Minister Ben Wallace - speaking in the Commons - suggested there had been failures in the baggage checks before the two suspects boarded a plane from Russia to the UK.
He added there was "no doubt" there would have been some checks on the Russian side of their journey but "the baggage checks weren't probably as good as they might be".
Mr Skripal and Yulia were poisoned in Salisbury in the UK in March.
"We know who they are, we have found them," Mr Putin said in the far eastern city of Vladivostok.
"I hope they will turn up themselves and tell everything. This would be best for everyone.
"There is nothing special there, nothing criminal, I assure you. We'll see in the near future," he added.
BBC Moscow correspondent Sarah Rainsford called Mr Putin's words a "tantalising hint" that the two men will speak "very soon".
"But the question of course is who will we see because don't forget that, in the UK, the suspicion is that the two names that were given are in fact aliases," our correspondent added.
Russian state TV says one of the suspects, Mr Petrov, told the channel he might comment publicly on the case next week.
'Simply sensational' - Russia reacts
By BBC Monitoring
Within minutes, Putin's remarks became top news on Russian TV, which called them "simply sensational".
On state TV's Channel One, a talk show speculated whether Theresa May would resign upon seeing that Petrov and Boshirov are not Russian hitmen after all, or whether the British government would come up with more "lies" to denigrate Russia.
Rossiya 1, another government-run TV channel, showed a beaming commentator saying he was "full of admiration for how Vladimir Putin is doing it", as the studio erupted in applause.
But the Kremlin's media machine suggested the most exciting news is yet to come - when the two suspects appear on TV in person and deal the final blow to accusations of Russia's involvement in the poisoning.
Scotland Yard and the UK's Crown Prosecution Service have said there is enough evidence to charge the men, who are understood to have travelled to London from Moscow on 2 March on Russian passports.
Two days later, police say they sprayed the nerve agent, Novichok, on the front door of Mr Skripal's home in the Wiltshire city of Salisbury, before travelling home to Russia later that day.
UK Home Secretary Sajid Javid has warned the men, thought to be aged about 40, will be caught and prosecuted if they ever step out of Russia.
The CPS is not applying to Russia for the extradition of the two men, as Russia does not extradite its own nationals.
But a European Arrest Warrant has been obtained in case they travel to the EU.
Det Sgt Nick Bailey also fell ill after responding to the incident in the city of Salisbury. He was later discharged from hospital, as were the Skripals.
Police are linking the attack to a separate Novichok poisoning on 30 June, when Dawn Sturgess and Charlie Rowley became unwell at a house in Amesbury, about eight miles away.
Ms Sturgess died in hospital on 8 July.
UK police said the two men arrived at Gatwick Airport from Moscow on 2 March and stayed at the City Stay Hotel in Bow Road, east London.
On 4 March they travelled to Salisbury - having also visited for reconnaissance the previous day - where Mr Skripal's front door was contaminated with Novichok.
Officers believe a modified perfume bottle was used to spray the door.
The pair flew back to Moscow from Heathrow later that night.
Police said Ms Sturgess and Mr Rowley were later exposed to Novichok after handling a contaminated container, labelled as Nina Ricci Premier Jour perfume.
Mr Rowley told police he found the box containing the small bottle and an applicator - all found to be counterfeit - in a charity bin.
He tried to put bottle and applicator together and got some of the contents on himself. His partner, Ms Sturgess, applied some of the contents to her wrists and became unwell.
The attack in Salisbury prompted an international row, with more than 20 countries expelling Russian envoys in solidarity with the UK, including the US, while Moscow expelled diplomats in response.
Last month the US confirmed it was implementing fresh sanctions against Russia over the incident. UK Prime Minister Theresa May has also said Britain will push for the EU to agree new sanctions.
Since the UK named the two suspects, US, France, Germany and Canada have agreed that the Russian government "almost certainly" approved the poisoning of the Skripals and have urged Russia to provide full disclosure of its Novichok programme.
In response, Russia accused the British authorities of Russophobia, misleading the international community and UK citizens and of "disgusting anti-Russian hysteria".