Scotland’s leading long-distance runner has had his national half marathon record invalidated after the organisers of the Great Scottish Run admitted the course length was 150 metres too short.

Callum Hawkins, 24, thought he had run into the record books in Glasgow last October but a remeasurement of the route has found it was 149.7m short of the required 21.1km (13.1 miles).

Hawkins, who came ninth in the 2016 Rio Olympics marathon, ran the course in 60 minutes and 24 seconds, breaking the previous Scottish half marathon record by 2min 4sec.

However, he and every other runner who ran a personal best time that day was told yesterday their times had been officially discounted.

Race organisers said the miscalculation was due to “human error” and a late change in the route because of roadworks.

Andy Mitchelmore, race director at The Great Run Company, said: “Great Run takes responsibility for the miscalculation and we apologise unreservedly to the runners and to the city of Glasgow. This was an isolated incident.

“In the 30 years since the company was formed, more than four million people have participated in hundreds of our running events and the distances, which are measured by qualified independent parties, have been correct.”

More than 30,000 people took part in the Great Scottish Run, completing the half marathon, a 10km race and a 2.5km junior race. Only the half marathon distance was incorrect, organisers said.

Half marathon runners who complained on Twitter and asked for a refund were told they would not get their entry fee back. Anyone who competed in the 2016 event will also be guaranteed entry in the 2017 race.

People who normally measure courses for us measure on closed roads

Concerns were first raised about the course length after runners crossed the finish line and found their personal tracking devices appeared to show they had not completed the official length.

A 50-metre section of the race was lost in Bellahouston Park when the original route plan was not followed correctly and a corner was missed and made into a straight.

David Hart, communications director for the race, said the remainder of the shortfall was a result of a late change made to the route because of public roadworks.

Mr Hart said that, because of the short notice given about the route change, they could not get the required permissions from the police and local authority to remeasure the route on closed roads before race day.

“A section of the course was measured when the roads were open,” he added. “We remeasured from mile four to 13.1 miles because at the start of the race we are going against the flow of traffic.

“People who normally measure courses for us measure on closed roads.

“This was August and they had to stick to pavements rather than taking the racing line. That accounted for 100 metres of the shortfall.”

To remeasure the course, four cyclists set off from George Square at 4.30am on Friday and finished in two stages at Glasgow Green at about 7am.

They were accompanied by a police escort whose job was to stop traffic. The riders’ bikes were equipped with specialist measuring equipment.

Hawkins, from Elderslie, Renfrewshire, was informed of the route miscalculation yesterday morning as he prepared to fly to Japan.

Mr Hart said: “We are extremely disappointed and obviously upset for him. The fact of the matter is he would still have absolutely smashed the record if he had run the other 150 metres.

“He and his family are understanding and will move on and we expect to see him take part in 2017. He has a half marathon in Japan this weekend and we would be absolutely delighted if he could break the record. He is in the best form of his life and still a young lad and the best is definitely still to come.”

The organisers said that a full road-closure remeasurement would take place if any changes were made to the route in future.