He told the Dáil he presented the evidence to GSOC after it was given to him by a serving garda whistleblower who, he said, was “terrified” that members of the force based in the Ombudsman’s office would expose his actions.

But the Roscommon TD said this worry “was significantly increased” after he was under surveillance when he went to the Ombudsman’s office.

Mr Flanagan said he was accompanied by another whistleblower, John Wilson. “It became obvious that we were under surveillance by an unmarked Garda car while waiting in the now infamous Insomnia cafe adjacent to GSOC’s premises,” he told the Dáil.

“John Wilson, who was there with me for support, left the cafe momentarily to establish what was going on. He was subsequently followed down the street by the unmarked Garda car,” he told the Taoiseach.

Mr Kenny said he had no information about any allegations relating to the drugs squad, but said Mr Flanagan was “a sharp man to know that an unmarked car was actually shadowing him.”

But Mr Kenny said he would deal with the allegations with “confidentiality”.

Mr Flanagan then accused the Taoiseach of belittling and making jokes about the serious issue.

“He needs to deal with this quickly because people are losing faith in what they have to have faith in, namely the Garda Síochána, he said.

After discovering they were under surveillance, the new whistleblower was “not terrified anymore, he was quivering, he was on the verge of breaking down.”

Mr Flanagan told Mr Kenny: “I bring it up here but you make a joke out of it. You are a disgrace.”