The Kremlin on Thursday slammed Britain's raft of punitive measures against Russia over the poisoning of a former double agent as “absolutely irresponsible".

“The position of the British side appears to us absolutely irresponsible,” President Vladimir Putin's spokesman Dmitry Peskov told journalists.

He said retaliatory steps would soon follow, with Putin likely to chose the option that “most suits Russia's interests".

On Wednesday, Britain said it would expel 23 diplomats and suspend high-level contacts with Russia, with other measures to follow.

The announcement came after British authorities said Russia was “culpable” of the poisoning of Sergei Skripal and his daughter with a Soviet-designed nerve agent called Novichok on March 4.

Peskov reiterated Moscow's position that Britain's accusations were unfounded and that the attack on Skripal had “all the signs of a provocation".

“The accusations are not backed up by anything and have been voiced before any information about the used substance could appear,” Peskov said.

Russian media accuses British PM of "poisoning" relations

Russian media on Thursday accused British Prime Minister Theresa May of having “poisoned” relations with Moscow by announcing the expulsion of diplomats in response to the poisoning of a former double agent with a nerve agent.

“Theresa May has poisoned relations between London and Moscow,” Nezavisimaya Gazeta headlined its front-page story.

Kommersant business daily accused Britain of seeking “toxic responses".

“The crisis in relations between Moscow and London has reached a new peak,” it said.

May “tried to accuse Russia of every sin under the Sun,” wrote popular pro-Kremlin tabloid Komsomolskaya Pravda. Another pro-Kremlin daily, broadsheet Izvestia, wrote that Russia will respond “at least in a symmetrical way” to the expulsions, meaning it would expel the same number of diplomats.

But “Russia's reaction could be also be more wide-reaching,” it predicted, citing diplomatic sources.

“Await a response,” Izvestia headlined its story.

“A seemingly emerging warming in relations with London has turned into a long-lasting frost,” wrote popular daily Moskovsky Komsomolets.

But it predicted that “Russia can bear it all without bowing down".

Former Russian spy Sergei Skripal and his daughter Yulia were found in a serious condition in the English city of Salisbury on March 4.

British experts say the pair were poisoned with a nerve agent which was developed by the Soviet Union during the Cold War.