The FA will not take formal action against Liverpool after its public display of support for the campaign to free Michael Shields, the fan serving a ten-year jail sentence for the attempted murder of a Bulgarian waiter in Istanbul in 2005.

The governing body wrote to the club for an explanation after players wore T-shirts with the slogan “Free Michael Now” before the televised match against West Ham United on Monday. Fans on the Kop also held up a mosaic calling for the release of Shields, 22.

"We have spoken to Liverpool Football Club today about this matter," an FA statement read. "We understand that Michael Shields' case is a very emotive issue and one that many Liverpool players and fans feel strongly about.

"Having heard the club's explanation we will not be taking any formal action, and we are satisfied that they understand the sensitivities around football matches being used as a platform for political messages."

Despite another man confessing to the attack, Shields was jailed but has since had his sentence was reduced to ten years on appeal. He was transferred to the UK to serve the remainder of his sentence, but his supporters have never halted their campaign to prove his innocence.

A judge at London's High Court decided last month that Shields' case should be heard in full by three judges and a judicial review hearing is due to begin tomorrow. Shields insists he did not commit the crime and still remains behind bars despite the best efforts of his family and various local politicians, who have campaigned for his release.

Earlier this year Bulgarian President Georgi Parvanov refused to pardon Shields and Justice Secretary Jack Straw has said that he had no power either to pardon or grant Shields an early release. A Fifa spokesman confirmed the organisation had been liaising with the FA over the matter and said the decision to not discipline the club was down to the host authority.