LONDON: General Mark Carleton-Smith, the head of the British army, has said that Russia was now a "far greater threat" to the UK's national security than the Islamic State (IS) terror group, the media reported on Saturday.

In his first interview since being appointed Chief of the General Staff in June, Gen Carleton-Smith said Russia was "indisputably" a bigger threat than Islamic terrorist groups like Al Qaeda and IS, the BBC reported.

"We cannot be complacent about the threat Russia poses or leave it uncontested."

The UK has blamed Russia for the poisoning of a former Russian spy and his daughter in Salisbury earlier this year. Democratic Party and a small TV network in Britain.

Russia denies any involvement in the spy poisoning and has described the cyber-attack accusations as a "rich fantasy".