The alarm was raised shortly before 9am on Sunday, around six hours before the match between Rangers and Celtic was due to kick-off.

Chief Superintendent Mark Sutherland, divisional commander for Greater Glasgow, said the incident involved supporters from both clubs and a probe has now been launched to investigate the circumstances.

Clubs urged to 'take action'

"I commend the work of our officers who acted swiftly in challenging circumstances to prevent escalation and disperse those intent on disorder," said Mr Sutherland.

"No arrests could be made at the time and we will now be investigating the circumstances. I would expect the footballing authorities and both clubs will do likewise and take appropriate action."

The Police Scotland chief explained that fans had been granted pre-arranged access to the stadium to set up displays, with Celtic supporters allowed in on Saturday and Rangers fans on Sunday.

A stewarding and policing plan had been put in place to support the arrangement, with security teams taking action to disperse the clashing groups on Sunday morning.

No arrests were made at the time.

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Chief Superintendent Sutherland added: "After the match police intervened or responded to a small number of incidents, including on Victoria Road, which were quickly resolved.

"Only four arrests were made for disorder-related offences and assault and I would like to thank the vast majority of supporters in attendance."

Celtic later won the match 2-1, lifting the first trophy of the season.