Former Taoiseach Bertie Ahern has said he does not have to "rehabilitate" his public image upon his return to Fianna Fáil.

Speaking to reporters, Mr Ahern said his "contribution" would be with the Taoiseach and Tánaiste on getting institutions in Northern Ireland "up and running".

"My whole intention is to be helpful to Government, helpful to the party in the North," Mr Ahern said.

"I don't have to rehabilitate myself anywhere."

Mr Ahern confirmed he re-joined Fianna Fáil "before Christmas" and said he did so as an "ordinary member".

"I have no intention of going back into my old job," he said.

Asked about if he would consider the presidency, Mr Ahern said: "My main job is to try and stay alive that long. It doesn't come up for a long, long time".

He said he joined the O'Donovan Rossa Cumann, of which he said he was a member for 41 years.

"It was following the discussions that took place at the parliamentary party where there was widespread support for me re-joining as a member," he said.

Mr Ahern added that this was followed-up by "a huge amount" of the national executive and councillors contacting him.

Mr Ahern rejected the suggestion his return was "divisive".

"My concentration will continue to be on the North, trying to get the institutions up and running, the whole issue around Brexit," he said.

Mr Ahern said he had been to conferences on Brexit for the last 10 years.

"I consider that my public service," he added.