Donald Trump’s Defence Secretary has accused Russia of “mucking around in other people’s elections” and violating international law.

General James Mattis made the claim following talks with his British counterpart, who accused Russia of “persistent interference” across the globe as tensions continue to rise between the Kremlin and the West.

Sir Michael Fallon said there “cannot be any return to business as usual” with Russia if the behaviour continues.

“There’s a pattern of interference now by Russia in different parts of the globe that needs us to be – when we engage with Russia – wary of what Russia is up to,” he told a press conference.

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“We need to be extremely watchful of this persistent pattern of Russian interference.”

Sir Michael said Britain would continue to work with Russia to avoid conflict in Syria, where Vladimir Putin’s forces are waging a bombing campaign in support of Bashar al-Assad while the US-led coalition supports anti-Isis opposition forces with air strikes.

General Mattis, who fought in the Gulf War, Afghanistan and Iraq before being picked for his role in the Trump administration, said he was “concerned” about Russian activity in Afghanistan and elsewhere.

“We look to engaging with Russia on a political or diplomatic level but right now, Russia is choosing to be a strategic competitor and we’re finding that we can only have very modest expectations of the areas where we can cooperate,” he said.

“It’s no longer a cooperative engagement with them.”

In pictures: Russian air strikes in Syria Show all 19 1 /19 In pictures: Russian air strikes in Syria In pictures: Russian air strikes in Syria Syrian boys cry following Russian air strikes on the rebel-held Fardous neighbourhood of the northern embattled Syrian city of Aleppo Getty In pictures: Russian air strikes in Syria Russian defense ministry spokesman Major General Igor Konashenkov speaks to the media in Moscow, Russia. Konashenkov strongly warned the United States against striking Syrian government forces and issued a thinly-veiled threat to use Russian air defense assets to protect them AP In pictures: Russian air strikes in Syria Syrians wait to receive treatment at a hospital following Russian air strikes on the rebel-held Fardous neighbourhood of the northern embattled Syrian city of Alepp Getty In pictures: Russian air strikes in Syria Russian Deputy Defense Minister Anatoly Antonov speaks at a briefing in the Defense Ministry in Moscow, Russia. Antonov said the Russian air strikes in Syria have killed about 35,000 militants, including about 2,700 residents of Russia AP In pictures: Russian air strikes in Syria Jameel Mustafa Habboush, receives oxygen from civil defence volunteers, known as the white helmets, as they rescue him from under the rubble of a building following Russian air strikes on the rebel-held Fardous neighbourhood of the northern embattled Syrian city of Aleppo Getty In pictures: Russian air strikes in Syria Civil defence members rest amidst rubble in a site hit by what activists said were airstrikes carried out by the Russian air force in the town of Douma, eastern Ghouta in Damascus, Syria Reuters In pictures: Russian air strikes in Syria A girl carrying a baby inspects damage in a site hit by what activists said were airstrikes carried out by the Russian air force in the town of Douma, eastern Ghouta in Damascus, Syria Reuters In pictures: Russian air strikes in Syria Civilians and civil defence members look for survivors at a site damaged after Russian air strikes on the Syrian rebel-held city of Idlib, Syria Reuters In pictures: Russian air strikes in Syria Civilians and civil defence members carry an injured woman on a stretcher at a site damaged after Russian air strikes on the Syrian rebel-held city of Idlib, Syria Reuters In pictures: Russian air strikes in Syria Volunteers from Syria Civil Defence, also known as the White Helmets, help civilians after Russia carried out its first airstrikes in Syria In pictures: Russian air strikes in Syria The aftermath of Russian airstrike in Talbiseh, Syria In pictures: Russian air strikes in Syria Smoke billows from buildings in Talbiseh, in Homs province, western Syria, after airstrikes by Russian warplanes AP In pictures: Russian air strikes in Syria Russian Air Forces carry out an air strike in the ISIS controlled Al-Raqqah Governorate. Russia's KAB-500s bombs completely destroy the Liwa al-Haqq command unit In pictures: Russian air strikes in Syria Caspian Flotilla of the Russian Navy firing Kalibr cruise missiles against remote Isis targets in Syria Â© TASS/ITAR-TASS Photo/Corbis In pictures: Russian air strikes in Syria Russia claimed it hit eight Isis targets, including a "terrorist HQ and co-ordination centre" that was completely destroyed In pictures: Russian air strikes in Syria A video grab taken from the footage made available on the Russian Defence Ministry's official website, purporting to show an airstrike in Syria In pictures: Russian air strikes in Syria A release from the Russian defence ministry purportedly showing targets in Syria being hit In pictures: Russian air strikes in Syria Russia launched air strikes in war-torn Syria, its first military engagement outside the former Soviet Union since the occupation of Afghanistan in 1979. Russian warplanes carried out strikes in three Syrian provinces along with regime aircraft as Putin seeks to steal US President Barack Obama's thunder by pushing a rival plan to defeat Isis militants in Syria In pictures: Russian air strikes in Syria Caspian Flotilla of the Russian Navy firing Kalibr cruise missiles against remote Isis targets in Syria, a thousand kilometres away. The targets include ammunition factories, ammunition and fuel depots, command centres, and training camps Â© TASS/ITAR-TASS Photo/Corbis

General Mattis said the US was attempting to diplomatically carve out room for manoeuvre so “Russia can change its behaviour and act in accordance with international norms and international law”.

“Russia’s violations of international law are now a matter of record, from what happened with Crimea to other aspects of their behaviour in mucking around inside other people’s elections,” he added.

His statements were in stark contrast to those made by Mr Trump, who publicly discredited a report by his own intelligence agencies that found Russia had interfered to turn the US election in his favour.

The President has also drawn criticism for making complimentary remarks about Mr Putin during his election campaign and the transition period.

Investigations continue into Russia’s alleged interference in the US election, which the Kremlin denies, as well as accusations of meddling ahead of the votes in Germany and France.

Tensions have been rising over Russia’s backing for President Assad in Syria, the Ukrainian war and a military build-up in competition with Nato.

Both Sir Michael and General Mattis issued a challenge for members of the military alliance to commit themselves to year-on-year increases in defence spending, calling for “fairer burden sharing” in the military alliance.

Nato has been building up forces in Estonia to deter Russian aggression (PA)

It came as reports suggested the Royal Marines may face cuts in response to a £10bn funding shortfall faced by the Ministry of Defence over the coming decade.

Sir Michael declined to rule out a cut in the elite commando units, telling BBC Radio 4’s Today programme that while he had not agreed any reduction in the size of the Royal Marines, numbers were kept “under review”.

But in his conference with General Mattis at Lancaster House, he stressed Britain’s military budget was growing every year and remains the largest among European Nato states.

The UK and US are among just five of the alliance’s 28 members to meet a target of spending 2 per cent of GDP on defence.

Mr Trump has repeatedly raised the issue, appearing to threaten the withdrawal of US funding after tense talks with Angela Merkel earlier this month.

Responding to previous allegations by Sir Fallon that Russia’s behaviour was becoming more “assertive and arrogant”, the Russian embassy in London dismissed his remarks as a “string of unfounded accusations”.

“Russia is an independent and sovereign state pursuing its national interest as defined by ourselves,” a spokesperson said, claiming that it was “clearing up the mess” made by Western states in Syria, Libya and Afghanistan.

Analysis by Kim Sengupta

The question was about Russia and Afghanistan --- James Mattis, unprompted, included in his answer the assertion that the Kremlin has interfered in democratic elections.

In his first visit to the UK since becoming Donald Trump’s Defence Secretary, Gen Mattis was gracious in talking about the special relationship, shared values, and this country’s supposed global role. He was careful to avoid talking about Brexit and looked mildly puzzled when, standing beside him, his British counterpart Sir Michael Fallon tried to maintain, with no great conviction, that Theresa May had not threatened to use security cooperation as a bargaining counter for a trade deal with the European Union.

But Gen Mattis was keen to talk about Russia. There will be no “return to business as usual" with Vladimir Putin’s government which “right now is choosing to be a strategic competitor” and “Russia’s violation of international law are now a matter of record”. He had “very modest expectations” of potential for cooperation. And he reminded a press conference in London “of their behaviour in mucking around inside other people’s elections and that sort of thing.”

This comes at a time when Washington is enmeshed in investigations into Donald Trump’s Russian connections and allegations that the Kremlin attempted to get a Muscovian candidate into the White House. In the latest development, Mr Trump’s national security advisor, former Lieutenant General Michael Flynn, has asked for immunity from prosecution in return for testifying to Congress about Russian meddling in the US presidential elections.

Gen Mattis had once presided over an investigation into Lt Gen Flynn himself. The proceedings in 2010 found that Lt Gen Flynn had shared “classified information with various foreign military officers and officials in Afghanistan without proper authorization.” It was reported last November that Lt Gen Flynn had personally crossed out Gen Mattis’s name from a list of candidates for security position in the Trump administration.