Prof Aidan Halligan has resigned from his post as director of clinical governance of the NHS in Britain.
His resignation from the NHS came after a letter to the British chief medical officer, Sir Liam Donaldson, was leaked to the press.
In it, Mr Halligan crticised reforms in the British health service and said that suggestions of real reform taking place were a deceit.
Mr Halligan had been offered the position of Health Service Executive CEO in 2004, but turned down the post.