The Foreign Office said Mr Johnson would visit Sergey Lavrov in the coming weeks - the first visit from a UK minister in more than five years.

His visit is described by Whitehall sources as part of a new policy of "guarded engagement" with Vladimir Putin's regime, but he faced criticism from MPs, who said Russia should remain isolated following its intervention in Syria.

Discussions would be "robust" on the issues of Russian intervention in Ukraine and Syria, and there would be no lifting of sanctions, according to the FCO.

A spokeswoman said: "The Prime Minister and Foreign Secretary have made clear that our policy towards Russia is to 'engage but beware' and the visit is entirely consistent with this approach.

"Discussions will focus on the UK-Russia relationship and current international issues including Syria and Ukraine, where we continue to have significant differences."

She added: "We have always been clear that the UK will engage with Russia where it is in our national interest to do so."

Official visit is "troubling"

Labour MP John Woodcock, chair of the all-party group on Syria, said: "It is troubling to contemplate an official visit to Moscow from the UK Foreign Secretary just months after Russia has committed grotesque war crimes in Syria as the world looked on.

"Russia can play an important role in upholding global security but until Putin is held to account for his butchery, the country ought to remain a pariah."

The FCO said a visit had been "in the pipeline for some time" and had been discussed by Theresa May and Mr Putin when they met in China in September last year.

Mr Johnson has publicly taken a hard line on Russia. Last autumn he said the Russians should be investigated for war crimes in the Syrian city of Aleppo, but the visit - the first by a UK minister since David Cameron and his then foreign secretary William Hague went to Moscow in 2011 - suggests a potential thaw in relations.

Sources said Mr Johnson would reiterate the tough criticisms he had made in Parliament in his face-to-face meetings and would not be "cosying up" to the Russians.

The timing is unfortunate however, given Britain's rejuvenated special relationship with Donald Trump's administration - several members of which are under fire for their ties to Moscow.

Speaking to an audience of Republicans in Washington in January, the day before she met Mr Trump, Mrs May declared that Britain would forge a different policy of "engage but beware" with Russia.

UK-Russian relations

Britain and other EU countries imposed visa bans and asset freezes on Russia after its annexation of Crimea from Ukraine in 2014, and full economic sanctions the following year.

Mr Johnson told EU foreign ministers in Brussels last month that there must be no let-up, and that he was concerned about the "recent upsurge of violence" in eastern Ukraine.

President Donald Trump has hinted in recent weeks that the US could lift its sanctions on Russia. An investigation is under way into alleged Russian interference in his campaign.

A report by the Commons Foreign Affairs Committee this week concluded that UK-Russia relations were at their lowest point since the Cold War.

The MPs warned that the UK could become "isolated" in its sanctions if other nations pulled away, while Crispin Blunt MP, who chairs the committee, welcomed Mr Johnson's visit and said he should use it to push for a political solution in Syria.

He added: "On ISIL (Islamic State), we need to co-ordinate with Russia to defeat a shared enemy in Syria and Iraq, and return stolen territory to their governments."

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