A crowd safety expert has claimed it was "just luck" that the outcome of last week's crush at Celtic Park was not more serious.

Professor Dr Keith Still said catastrophic organisational failures had put supporters' lives at risk ahead of the Old Firm match.

Mr Still examined video and photo evidence and fans' testimonies, and visited Celtic Park to look at the concourse at Janefield Road where the North Stand overhangs the road.

He said it was clear "three times" the safe amount of fans were packed into the area last Sunday.

Five fans were hurt and dozens had to climb over fences and walls to escape the crush as panic spread through the crowd.

Both the police and the club are investigating the incident.

Celtic announced on Friday that they have drafted in safety consultants to carry out an independent review.

Mr Still, a professor of crowd science at Manchester Metropolitan University, told the Sunday Mail: "The density of fans appears to be six to seven people per square metre - three times the maximum safe level of about two per square metre.

"At too high density, any trip, slip or fall means people do not have the opportunity to react safely - and this can have a catastrophic effect.

"It's just luck that the outcome wasn't worse."

Chief Superintendent Brian McNulty, divisional commander for Greater Glasgow, said the safety of fans is an "absolute priority".

He praised staff on the ground that day for "acting quickly" to prevent the situation worsening, adding: "We will continue to work with Celtic FC and with supporters to learn from Sunday and improve future operations."

Celtic said it has instructed Fairhurst, consultants in sports event safety management, to examine the incident and urged any fans with information to come forward.