Shields was jailed in Bulgaria in 2005 for the attempted murder of a barman following Liverpool FC's European Cup victory in Istanbul, Turkey.

Despite another man confessing to the attack, Shields was locked up for 10 years.

He was transferred to Britain to serve the remainder of his sentence, and is currently held at HMP Haverigg in Cumbria.

In a provisional decision, Mr Straw was unable to conclude Shields was "morally and technically innocent", the Ministry of Justice said.

A High Court judgement in December last year set a "very high" bar for granting what is known as a free pardon.

A Ministry of Justice spokesman said Mr Straw had written to Shields to give him a "full explanation" of the reasons for his decision.

Shields can make further representations to the Justice Secretary, after which he will make a final decision.

Mr Shields' father, Michael, said his 22-year-old son is "absolutely distraught" by the decision.

He said: "I don't know what I am going to do. We are going to have to discuss our next step. I think we have 28 days to try to convince them they're wrong."

Fighting back tears, Mr Shields' mother, Marie, added: "I just can't believe it - it's a disgrace, this feels like a knife in the back.

"I don't know how much Michael can take."

Hopes were raised at the beginning of June when Prime Minister Gordon Brown promised the Shields family they would have news by the end of the month.

But the latest decision comes as a blow to the Shields family and thousands of their supporters who have campaigned for the fan's freedom.