A former Fine Gael TD has denied his brother was involved in a verbal confrontation with Sinn Féin deputy leader Mary Lou McDonald.

A man - who identified himself as a “concerned citizen” - challenged Ms McDonald in Dublin on Friday, accusing her party of planning to “kill pensions” and tax high earners out of existence.

It was later reported that the man was Fergus Crawford, chief executive of a multi-national investment firm.

It was also claimed in the press and on social media that the man was the brother of Seymour Crawford, the former Cavan-Monaghan TD.

“I wish to state that my two brothers are dead; John in 1998 and the Revered Joe in 2014,” the former Fine Gael deputy said in a statement on Monday morning.

“I take serious exception to the fact that my name has been linked with Mary Lou McDonald’s encounter with a member of the public last week.

“On Facebook and other media, accusations were made that the man who questioned Mary Lou McDonald was a brother of mine and that this incident was organised by Fine Gael.”

Ms McDonald accused the man who approached her as having a brass neck. “The bankers, developers, all of the crew who wrecked this place have now regrouped, and they are now sufficiently emboldened to challenge people like me on the streets of Dublin on the basis of, ironically, our ability to protect ordinary people,” she said.