"Moscow does not accept unfounded accusations that are not based on evidence and a language of ultimatums," Kremlin spokesman Dmitry Peskov told reporters.
"We are hoping that common sense will prevail," he said in the Kremlin's first public response to British accusations that Russia was likely behind the attempted murder of former double agent Sergei Skripal.
On Tuesday, Foreign Minister Sergei Lavrov rejected British Prime Minister Theresa May's deadline to explain how a Russian former double agent was poisoned in Britain with a highly toxic nerve agent invented by Russia.
"Moscow has nothing to do with the accident in Britain," Peskov said, reiterating Moscow was open to cooperate on the investigation.
He declined to comment on reports in the Western media on the possibility of invoking NATO's Article 5 principle of common defence, saying Moscow hopes other countries would see there was no evidence to blame Russia for the poisoning attack.
"As far as a threat of isolation is concerned, we are hoping that common sense will prevail and other countries will at least think whether there is any proof or not and just how justified the rebukes against Moscow are," Peskov said.
London is mooting possible punishment against Moscow, with British communications regulator Ofcom saying it could review the licence of the Kremlin-backed RT broadcaster if Russian involvement in the poisoning was proven.
"Any illegal actions against any Russian media outlet in the United Kingdom will lead to retaliatory steps on the basis of reciprocity," Peskov said.
"What steps will it be? These would be steps that best suit Russia's interests," he added.
In a terse comment earlier this week, Putin told the BBC: "Sort things out from your side and then we will discuss this with you."
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