The head of Britain’s MI6 spy agency has accused Russia of being the main contributor to an “unprecedented” terrorism threat that he says the UK is currently facing.

In his first public speech since taking office in 2014, Secret Intelligence Service boss Alex Younger said that Moscow’s military efforts against ISIS terrorists in Syria were threatening the security of Britain.

Speaking to journalists at the MI6 headquarters in London’s Vauxhall, he attacked Russia for backing Assad’s “discredited” Syrian regime, warning that defining opponents as terrorists alienated people who must be brought onside if extremists are to be defeated.

Mr Younger called on the Kremlin to halt its campaign in the besieged and starving city of Aleppo.

His remarks came as Syrian government forces made significant gains in retaking the terrorist strongholds in the city.

Press TV reports:

“I believe the Russian conduct in Syria – allied with that of Assad’s discredited regime – will, if they do not change course, provide a tragic example of the perils of forfeiting legitimacy,” he said.

“We cannot be safe from the threats that emanate from that land unless the civil war is brought to an end,” the spymaster said of Syria’s years-long struggle with foreign-backed militant groups.

He made the remarks as the Damascus government has made significant victories in purging Takfiri terrorists from militant-controlled areas of the Syrian city of Aleppo, one of the group’s main strongholds.

Pointing that British security forces had disrupted 12 terrorist plots since June 2013, Younger said Daesh had developed a “highly organized external attack planning structure” to attack the UK and other Western countries “without ever having to leave Syria.”

In another tongue-in-cheek jab at Russia, Younger blasted countries that have been trying to undermine Western governments through cyber attacks.

The US government has also leveled such charges against Moscow. The accusations reached their peak during this year’s presidential election cycle.

Democrats and the government of US President Barack Obama constantly accused Russia of trying to disrupt Democratic nominee Hillary Clinton’s campaign and influence the election in favor of President-elect Donald Trump.

“The connectivity at the heart of globalization can be exploited by states with hostile intent to further their aims of deniability. They do this through means as varied as cyber-attacks, propaganda or subversion of democratic process,” the MI6 chief said.

Younger’s remarks against Russia were in contrast with Trump’s view of Syria, who deems Moscow as a key player in the fight against terror in the Arab country.

Over the past few months, London has been constantly calling on the EU to unite and repel the “Russian aggression” by deploying more military forces in Eastern Europe.

The anti-Russian rhetoric has angered the Kremlin, with Russian Defense Ministry spokesman Igor Konashenkov dismissing the allegations as “Russophobic hysteria.”