Police investigating an attempted murder following Sunday's Old Firm game that left a man fighting for his life are following a positive line of enquiry.

The 47-year-old victim remains in a critical condition after he was stabbed in Merchant City in Glasgow.

Two other people were also left badly injured during the brawl on Blackfriars Street but have since been released from hospital.

The incident took place at around 5pm just a few hours after the Celtic vs Rangers game in nearby Parkhead.

Investigating officers are appealing for information including mobile phone footage that they say could be crucial to catching those responsible.

Detective inspector Peter Crombie said: "The 47 year-old sustained very serious injuries in this attack, and is still in a critical condition. His family are distraught.

"We are doing everything we can and are particularly looking for mobile phone footage of the incident as it could be the crucial piece in this investigation.

"You may think that someone else will have got in contact so you don't have to, this is not the case and we need to speak to everyone who was there that evening and witnessed this incident.

"We want to thank those who have come forward in the past few days and would continue to encourage those who have not to get in touch with us via 101."