A SECOND inquiry into allegations that police officers have lied on the stand in cases involving football fans is under way.

Our sister newspaper The Herald reports that Police Scotland has confirmed it is investigating claims an officer within its dedicated football unit committed perjury in a case where two supporters were found guilty of singing offensive songs.

It followed a complaint lodged with the force by a member of the public accompanied by Labour MSP Paul Martin and centres on allegations the officer was aware evidence given in the conviction of two men that warnings had been issued to fans about certain songs was inaccurate.

Two other police officers, a chief inspector and sergeant, remain under investigation following perjury allegations in a case where a football fan was acquitted of his role in a notorious incident.

The pair had given evidence against a youth charged with breach of the peace for his role in the kettling of Celtic fans on Glasgow's Gallowgate in March 2013.

The latest case involves Celtic supporters William Donnelly and Martin Walsh, who were charged with engaging in behaviour which was likely or would be likely to incite public disorder by singing a song in support of a proscribed terrorist organisation. The two men were given six-month football banning orders.

The "Roll of Honour" song commemorates Irish Republican hunger strikers from the Provisional IRA and Irish National Liberation Army (INLA).

It has been alleged that evidence given by an officer within the Football Coordination Unit Scotland in the initial conviction and cited in the refusal of their appeal was knowingly incorrect.

During the trial the officer had said Celtic and various supporters' clubs had warned fans of the undesirability and dangers in singing this particular song and that the pair were therefore aware the song was banned.

But various documents dispute the claim that fans' groups ever publicly indicated the song was sectarian or otherwise.

Celtic did have a meeting with the police where it was indicated fans would face potential arrest if they sang Roll of Honour but this was a month after the game where Mr Walsh and Mr Donnelly committed their offence.

A letter to Jeanette Findlay, a prominent member of the pressure group Fans Against Criminalisation who made the complaint to Police Scotland, states that an officer with the force's professional standards unit has been appointed to investigate the complaint.

The complaint also follows almost seven months of attempts to have the Crown Office's dedicated unit which examines criminal allegations against the police investigate at the claims, including direct contact between Glasgow MSP Mr Martin and Lord Advocate Frank Mulholland.

Ms Findlay said she only made the allegation in person to Police Scotland after the Crown Office "failed consistently to respond to me regarding serious allegations".

A spokeswoman for Police Scotland said: "As this is an ongoing investigation, we are unable to comment at the present time."

The two men involved in the case, both from Dumbarton, were prosecuted after the incident at Hibs' Easter Road stadium in October 2013. They later took their case to the appeal court in Edinburgh, claiming their rights under the European Convention of Human Rights had been breached.

However, the Lord Justice Clerk, Lord Carloway, sitting with Lord Bracadale and Lord Boyd of Duncansby, refused the appeal earlier this year.