Britain's biggest amateur road cycle race, featured as part of the Scottish government's Homecoming celebrations, was halted yesterday after locals allegedly spread carpet tacks across the roads.

More than 3,700 people were taking part in the Étape Caledonia in Perthshire, which is inspired by the hugely popular Étape du Tour, an event that allows amateurs to ride a stage of the Tour de France.

The charity race runs over 81miles (130km) of countryside around Pitlochry. It is the only cycle event in Britain where all the roads on the route are closed - for three hours - which has apparently provoked some to sabotage.

Hundreds of tacks were strewn on a section of the race from Rannoch to Aberfeldy, bursting tyres. Police described it as a reckless act. After a delay, organisers swept the road and the race was completed.

The winner, Veli-Matti Raikkonen, who is from Finland and is a member of Aberdeen's Granite City racing team, was one of those who suffered a puncture. The lead group suffered punctures on a section of road at Innerhadden and Schiehallion, about 43 miles into the course.

Organisers of the race said that they were working with police to discover what had happened. “It is really not acceptable that this kind of behaviour is allowed to happen,” said one.

A spokesman for Tayside Police said: “It was fortunate no one was injured. Uniformed and detective officers are carrying out inquiries in the area and are following a positive line of inquiry.”

The event, whose entries have almost doubled since last year, has developed into the Perthshire Cycling Festival but has brought protests over the disruption.

Kathy James, one of the organisers, who runs a bed and breakfast in Aberfeldy, said that the race brought millions of pounds to the area. She told BBC Scotland: “This area relies on tourism, it disgusts me as a local.”

In 2008, an independent survey revealed that the race boosted the local Perthshire economy by £416,885.

The event, which was expected to raise £225,000 for Macmillan Cancer Support, was open to anyone aged 18 to 80. The route ran from Pitlochry, along Loch Tummel and round Loch Rannoch, returning via Glen Lyon to Aberfeldy and Pitlochry.

Participants were told they needed to maintain an average speed of 13-14mph around the course in order to reopen the roads within the given time. Among those taking part were the Sky News presenter Dermot Murnaghan and Georgie Thompson from Sky Sports News as well as 12 members of the British Alpine Ski team, who were aiming to raise £5,000 for charity.

This year, Étape Caledonia has featured as part of the Scottish government's Homecoming campaign and has attracted sponsorship from Macmillan Cancer Support, Highland Spring and Adidas.

Entries for the race closed in March and over half of the cyclists taking part travelled from outside Scotland.

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