The Minister for Justice, Mr O'Donoghue, has said the official in his office who made contact with Mr Justice O'Sullivan was "entirely blameless" in the matter.
Mr O'Donoghue said the Department of Justice official was merely facilitating a request from the office of Minister of State for the Environment, Mr Bobby Molloy.
The official was asked whether correspondence had been received in the name of Ms Ann Naughton, the sister of the Connemara man jailed for the rape of his daughter.
The official did not know what the matter was about and he didn't know why Mr Molloy's office wanted the judge's number. "It could have been about any matter under the sun," he said. It would have been gravely discourteous of the official not to have facilitated the request. The individual involved acted in good faith.
It was not unusual for officials in the Department to make contact with judges, the Minister told RTÉ News. "Let's not ascribe a motive when it wasn't there."
Mr O'Donoghue criticised the Fine Gael and Labour leaders, saying they were trying to impugn his integrity. "Character assassination seems to be the order of the day in some people's lust for power," he said.
There were no circumstances in which he would facilitate improper contact with a judge, or interfere with the judiciary.