Scotland's chief legal officer has told prosecutors to stop using the Offensive Behaviour Act, STV News has learned.

The Lord Advocate, James Wolffe, updated guidelines earlier this month to instruct the Crown Office and Procurator Fiscal Office (COPFS) to use pre-existing statutory offences or common law, such as breach of the peace.

Scottish Labour MSP James Kelly, who has tabled a private member's bill to repeal the law, called the move a "significant development".

MSPs will take a final vote on whether to repeal the legislation on Thursday, but there is little doubt there will be a majority in favour of ripping up the Act.

The SNP are the only party in favour of its retention at Holyrood, with the pro-repeal parties making up a majority in the chamber.

In his guidance, the Lord Advocate said: "Criminal offences committed at, or in connection with football, which may previously have been reported using section 1 or section 6 of the 2012 Act should therefore be assessed in terms of other existing alternative common law or other statutory offences and, where there is a prima facie sufficiency of evidence, reported using those alternative offences.

"Behaviour at football matches can, in certain circumstances, constitute an offence under legislation such as Section 38 of the Criminal Justice and Licensing (Scotland) Act 2010, threatening or abusive behaviour or under the common law, for example as a breach of the peace or culpable and reckless conduct."

None of the six people arrested at Sunday's Old Firm clash in Glasgow were held under the Act.

The move to effectively stop using the legislation will likely be seized upon by its opponents, who will point it has been deemed effectively unnecessary by the Lord Advocate already.

A spokesman for the COPFS told STV News: "COPFS deals with every report received on its individual facts and circumstances and will take action where there is sufficient evidence and it is in the public interest to do so.

"COPFS have reviewed and amended internal prosecution guidance and the published Lord Advocates Guidelines given the progress of the Offensive Behaviour at Football and Threatening Communications Repeal Bill through the Scottish Parliament."

A Scottish Government spokesman said: "Prosecution policy and guidelines are a matter for the Lord Advocate and the COPFS.

"However, we remain concerned at potential gaps in the law if repeal goes ahead and believe repeal will compromise the ability of police and prosecutors to charge people for unacceptable behaviour at football."

Kelly said: "Repeal of the Football Act does not mean that people behaving in a criminal manner will be let off.

"If anything, it will clear up the legal process and end the injustices caused by the illiberal basis of the Football Act.

"There will be no gap in the law as a result of repeal, so the challenge for the Scottish Government now is to set out how they will make progress in actually tackling sectarianism.

"While ministers have desperately defended this broken law, they have cut funding for anti-sectarianism initiatives - investing in education must be the way forward."