A controversial mass cycling event has been hit by saboteurs – for the second time this year.

Thousands of cyclists swarmed on the New Forest for the Wiggle New Forest 100 Sportive event over the weekend. But during the dead of night opponents of the race ripped down signs and tried to block routes by spraying mud on the road.

The unknown group of anti-cyclists activists were aiming to put the brakes on the event which features three routes ranging in length from 41 to 102 miles through the National Park.

Organiser Martin Barden said cyclists could have been endangered and said his team were forced to make constant checks to keep one step ahead of the saboteurs. He said: “I believe they were a handful of very passionate people who doing it with good intentions but were not going about it in the right way.

“There was potential for serious injury to cyclists.”

Mr Barden said his team discovered that Pinkney Lane in Bank had been swamped in thick mud early on Saturday morning, forcing them to turn the course around it amid fears cyclists would skid off the road.

It is believed a local farmer may have been involved. The activists also went round ripping down speed limit signs on roads and other route information.

Mass cycling events in the Forest have been at the centre of controversy and earlier this year anti-cyclists activists scattered scores of tacks on to the route of a similar event, ripping up hundreds of route signs.

Starting in New Park in Brokenhurst, it has also has led to the annual pony drift, which is being held on neighbouring land, being cancelled last weekend amid safety fears.

Motorists, residents, horse-riders and commoners also fear the events risk damaging the Forest’s wildlife, flora and fauna, and cause hazards for other road users. The Commoners’ Defence Association (CDA), which represents the owners of the Forest’s ponies, have criticised Wiggle organisers in the wake of the decision to axe the round-up of wild horses.

But UK Cycling Events hit back, accusing the Verderers of failing to give enough advance warning of the round-up. National Park Authority (NPA) member Barry Rickman said he was against people trying to sabotage the race. He said: “I can’t condone extremist behaviour. There is no winner in that sort of game.”

But he said he understood there was strong feeling against mass cycling events among some people living in the Forest.

He said: “There is no doubt the significant effect it has on local motorists. I have been out on the road in the last couple of days and there is has been a considerable effect on local people.

“I think local people are thinking into the future and thinking ‘Is every weekend going to be like this?’”