"All that raises very serious questions over the safety of his conviction. The evidence to convict him simply was not there.
"My comments in the House of Lords had cross-party support and the government was left in no doubt there is widespread concern about what has happened to Michael.
"He remains very much in my prayers."
Baroness Royall of Blaisdon, a government minister in the Lords, said: "Now this judicial process has ended, I believe it can be taken to the European Court of Human Rights."
That would be on the grounds that the Bulgarian Supreme Court refused to consider new evidence pointing to the Reds fan's innocence and the lack of witness and forensic evidence in the original trial.
Michael was jailed for 15 years for attacking a barman, despite another Liverpool man confessing to the attack in the Black Sea resort of Varna.
