A decision will be made this month on whether to grant jailed Liverpool fan Michael Shields an official pardon, UK prime minister Gordon Brown has indicated.

Barman Martin Georgiev had a rock dropped on his head in Varna in May 2005. Shields was found guilty of attempted murder by a Bulgarian court after the incident but has always maintained his innocence

Shields, 22, was transferred to the UK in 2006 after his 15-year sentence for the attempted murder of barman Martin Georgiev in the Black Sea resort of Varna was reduced on appeal.

Justice Secretary Jack Straw has the power to issue a pardon but has asked police to examine the Bulgarian conviction.

Brown told the House of Commons that Straw would make the "best and fairest decision" he could. The prime minister was responding to a powerfully-worded question from Riverside MP Louise Ellman, who has been involved in the four-year campaign to win justice and a pardon for the 22-year-old Liverpool fan.

Shields' supporters, who include Liverpool players, clergy, politicians and several prominent showbusiness personalities, were buoyed by last year's high court ruling that Straw had the power to order his release.

But one of Shields' supporters, Councillor Joe Anderson, criticised the length of time the decsion was taking: "The prime minister has told us on several occasions he is aware of people’s concerns and the length of time they have been waiting for a decision...Jack Straw commissioned the police report personally and waiting a month when the inquiry finished three weeks ago is not acceptable. How long does it take for highly-paid Queen’s Counsel to reach a decision after reading the statements? I have read War And Peace twice in that time."

Anderson said that Shields was feeling depressed in jail. "On Saturday, Michael reached the sad milestone of four years incarcerated for a crime he did not commit. He is at a very low ebb at the moment. The best years of his life have been spent in prison. He turned 21 there. It is a huge embarrassment to this country and I would have thought it would be a case of hours or at most days for them to scour the report, not weeks."