CYCLISTS have voiced concern after nails and tacks were found littering the road during a major Scottish event.

Organisers of the 2015 Pedal for Scotland 50-mile ride from Glasgow to Edinburgh confirmed that the incident took place between Limerigg and Avonbridge in Stirlingshire at around 9.30am on Sunday.

It is believed that at least 50 cyclists were affected in what appeared to be a deliberate attempt to disrupt the event.

Many participants took to Facebook and Twitter to vent their frustration with some accusing organisers Cycling Scotland of trying to play down the incident.

Alpine Bikes, which provided mechanical support along the route, confirmed it took more than four hours to work through the "challenging" volume of cyclists that had sustained punctures.

Andy Butler, senior buyer at Alpine Bikes, said: "It soon became apparent that there was a protest incident round Avonbridge where our two mechanics were inundated with people who had punctures.

"Tacks had been dangerously placed on a fairly narrow road, causing up to 50 punctures within a short space of time.

"Extra mechanics were sent in to help out and additional inner tubes provided, but it was challenging to cope with the volume of people and the number of tacks we pulled out of tyres."

Despite drafting in additional pairs of hands, Mr Butler said his mechanics had to work flat out to get the affected cyclists back on the road.

"The tack incident caused a constant queue of around 30 people for more than four hours, even though each mechanic was finishing a repair every five minutes," he said.

"Some very sporting riders even stopped to pick up tacks in an attempt to clear the road – whoever those people are, we are grateful."

Kenny Laird, 48, from Glasgow was among those who witnessed the incident between miles 23 and 24 on a remote stretch of road shortly before the feed station at Avonbridge.

"There was lots of people, one after the other, stopped at the side of the road with punctures," he said. "It was a mixture of carpet tacks and slate nails. I heard of someone who got one in their knee. They must have come off [the bike] in among them.

"I was fortunate enough to avoid getting a puncture but I passed at least 30 small groups of people helping each other. My wife, who was also cycling, said she could hear the hiss of people's tyres going down around her."

Around 9,500 people cycled during Pedal for Scotland which included more than 7,000 on the 50-mile Classic Challenge. There was 600 on the 110-mile Big Belter through the Southern Uplands, while 1,000 others took part in the Wee Jaunt Glasgow on Saturday.

Celebrity riders included round-the-world-cyclist Mark Beaumont, Capital FM breakfast DJ Jennie Cook and STV weather presenter Sean Batty.

This year marked the first time that the 50-mile ride had taken place on an entirely traffic-free route.

Keith Irving, chief executive of Cycling Scotland, said: "Over the weekend, 9,500 people had a fantastic time cycling across Scotland with Pedal for Scotland.

"Friends, families and colleagues were raising money to tackle child poverty and there was great and enthusiastic support from spectators in many of the towns and villages along the route.

"We regret that the action of a mindless minority has caused problems for event participants who have been affected.

"The operational team helped remove the tacks after they were reported and all information we have has been shared with Police Scotland."