Theresa May is to meet Russian president Vladimir Putin at this week's G20 summit in Japan, Downing Street has announced.

But Number 10 played down suggestions that the meeting on Friday will mark a thaw in British-Russian relations, which have been in the deep freeze since last year's chemical attack in Salisbury.

The prime minister's official spokesman said the PM would take the opportunity to restate her concern about Russia's "pattern of malign behaviour", including the poisoning of former spy Sergei Skripal and his daughter Yulia with nerve agent novichok.

The spokesman said Ms May would make clear that the UK was open to a less frosty relationship with Russia if Moscow gives up activities which undermine international security, but added: "This meeting does not represent a normalisation of relations."

A spokesman for Mr Putin said that the pair would discuss “sensitive questions” around the British-Russian relationship and appeared to indicate that the Kremlin was willing to explore the opportunity for a thaw.

Kremlin aide Yuri Ushakov told a media briefing in the Russian capital: “The leaders will talk over sensitive questions. As you know there are many of them.

“If any kind of opportunity can be found in our relations with Britain to establish new co-operation, then we will only welcome that.”

Police outside Sergei Skripal's house in Salisbury (Getty)

Ms May's spokesman told a Westminster media briefing: "The prime minister's position on Salisbury and Russia's wider pattern of malign behaviour is well-known. As she has said, we are open to a different relationship but that can only happen if Russia desists from activity that undermines international treaties and our collective security, like the attack in Salisbury.

"This meeting is an important opportunity to deliver this message leader-to-leader to ensure the UK's position is fully understood. Of course, there are matters of international security where we continue to engage with Russia when it is in our national interests to do so.

"This meeting does not represent a normalisation of relations."

Ms May is making her final scheduled appearance at a major international summit when she represents the UK at the G20 gathering of major economic powers in Osaka on Friday and Saturday.

She last spoke with the Russian president when he approached her on the margins of the last G20 leaders’ summit in Argentina last November.

UK-Russian relations sank to a post-Cold War low following the poisoning of the Skripals in March 2018 and the subsequent death of Dawn Sturgess, who is believed to have come into contact with novichok discarded by the alleged attackers.

Britain said it was “overwhelmingly likely” that the attack was ordered directly by Mr Putin – something the Russian president has denied.

Russian president Vladimir Putin appears on his annual nationwide TV phone-in show in Moscow on Thursday (Reuters)

Countries around the world expelled a total of more than 150 Russian diplomats in solidarity with the UK.

Mr Putin said earlier this month that he hoped Ms May's successor as PM would forget the Salisbury affair.

“When all’s said and done we need to turn this page connected with spies and assassination attempts,” the Russian president said at an economic forum in St Petersburg.