The Kremlin attempted to undermine relationships between Britain, Ireland and the European Union during Brexit negotiations, including trying to set up secret meetings with loyalist terrorists, it has been claimed.

The Sunday Times said the meetings had been arranged after Russia targeted an Irish politician, who is, they say, still in government, through a ‘honeytrap’.

While the newspaper did not name the politician involved for legal reasons, it said the politician, referred to as ‘Cobalt’, had engaged in meetings with Sergey Prokopiev, a Russian spy who worked out of the Russian embassy in Dublin between 2019 and 2022.

In a meeting outside Dublin it was claimed ‘Cobalt’, who was under surveillance by the military and the Irish police, offered to connect the Russians and paramilitaries in Northern Ireland at a sensitive time in the Brexit talks.

The attempt was made during a period when Loyalist paramilitaries were threatening violence over the 2019 and 2020 Brexit deals, which created a customs border in the Irish Sea, to prevent a land border between Northern Ireland and the Republic.

Taoiseach Simon Harris said on Sunday he would not comment on matters of security, but admitted it should be “no surprise” that Russia was seeking to influence

“Other than to say more broadly, it shouldn’t come as any surprise to any of us that Russia seeks to influence public opinion, seeks to distort public opinion and is active in relation to that across the world and that Ireland is not immune from that,” he said.

“We’ve also seen a very significant increase in that level of activity since the brutal invasion by Russia of Ukraine.

“Gardai and our security services take all of these issues extremely seriously and monitor these issues seriously, and work with international counterparts on all these matters, and I have great confidence in the ability of gardai, working with international counterparts.”

Pressed on whether he knows who the alleged agent is, Mr Harris said: “We never comment on this kind of thing. I’m not sure of any country does comment in relation to security matters.

“But I can tell you that as Taoiseach I am satisfied that our gardai and our intelligence services working internationally with counterparts take this issue very very seriously.”

Security chiefs believe that ‘Cobalt’, who has received no payments from the Russians, was recruited as part of a honeytrap operation, where an enemy intelligence officer or agent lures the target into compromising sexual encounters as several meetings between Cobalt and a female agent were logged.

She was monitored entering the state on several occasions for short periods, but no action could be taken as ‘Cobalt’ was not breaking any law.

The Sunday Times said the public figure’s internet history, intercepted during travels abroad, played a key role in securing information against him.

According to flight data, ‘Cobalt’ travelled to countries outside the European Union where the Russian intelligence ­services operate freely.

“They used him but he allowed himself to be used,” a security source said.

The politician was approached by Irish special branch officers and formally warned that he was being targeted by the Russians. His dismissal of those concerns strengthened their suspicions about his activities.

Prokopiev, a colonel in the GRU Russian military intelligence, worked undercover as a counsellor at the Russian embassy.

He was one of four Russian diplomats kicked out of Ireland in 2022 after being identified as undeclared intelligence officers, parts of a wave of 600 expulsions of Russian spies across the West after the invasion of Ukraine.

‘Cobalt’s’ recruitment is the first known infiltration of the Irish parliament by a hostile intelligence service in modern times but follows several efforts to compromise politicians in the UK as part of Russia’s “active measures” to destabilise western society.

‘Cobalt’ could not be arrested or charged with espionage because he did not have access to any classified material, therefore could not disclose its contents to a hostile state.

The security services believe he was used as an asset – an easily influenced person who could make introductions, disrupt public debate or air the Kremlin’s views when prompted.

He remains a person of interest to Garda intelligence and J2, the military intelligence branch of the Irish defence forces.