The Minister for Justice has ordered an inquiry into the circumstances of how a prisoner at the country’s maximum security jail managed to phone RTÉ's Liveline radio programme on a mobile phone from his cell.

Michael McDowell said he was very deeply concerned at this brazen and deliberate breach of security.

He has asked the Director of Prisons to furnish a report to him as soon as possible and he said somebody has to be accountable and take personal responsibility for it.

The minister said it was the second major breach of security in an Irish prison today; earlier officers searched a cell in another prison and found a number of phones and DVD players.

Mr McDowell said there may be a question of complicity by prison staff in these breaches of security.