A series of items – including cables or string stretch neck height, branches and rocks – were found by marshals left in on a course due to be used in a race this weekend.

Marshals set to work at an MTB race today, Sunday, found a series of obstacles strewn across the course in an apparent bid to booby trap it.

String or cable was found stretched head or neck height across the Co Down course and large larges and parts of trees had also been left in the path of the riders.

The items were found in Kilbroney, Rostrevor, yesterday just 24 hours before today’s First Tracks Enduro Cup race at the venue.

Organiser Glyn O’Brien told BBC Nortern Ireland that the local police were aware of the incident and were investigating it, adding officers had told him they would check the area last night before today’s event.

“It’s obviously extremely dangerous for any competitors that come down,” race organiser Glyn O’Brien told the BBC.

“It just gives a bad vibe really with mountain bikers in the area.”

“We’re not really sure if this is kids doing this for fun or something a bit more malicious,” he said, adding what was found would be very dangerous had the riders raced into it.

He also believed the use of string or cable suggested the incident was planned.

“It’s not the sort of thing that a person carries on them when they’re walking in the hills and not something that was lying about,” he said.

“So the person has deliberately done this, they have thought about what they’ve been doing and moved all the big rocks and logs as well and they’ve taken their time – it wasn’t a five-minute job.

“It’s extremely scary to think anybody would do that.”

A large log left across the track.

Another part of a tree that looks as if it has been placed on the trail.

Blue string was placed on one part of the course; it would probably break on impact but could still cause nasty injuries or knock a rider travelling downhill at speed off their bike.