Mountain bikers say a purpose built cycle track on Wearside has been booby trapped and could cause them serious injuries.
The fears centre on the track at Penshaw Monument, which riders say has been deliberately targeted by people leaving pieces of wood with nails sticking out on the course.
Cyclist Dan King, 23, from Houghton, spotted traps and says they could cause serious injury should someone fall on the - as well as causing punctures.
Mr King, a former Army rifleman, said he had been using the track for over 10 years.
He said: “There is a group of us who meet up for a social ride on the track but recently we have seen traps left for cyclist and even a sign that say’s ‘there’s more.’
“The first trap I saw was on Thursday, February 16 and then I saw another one the following Saturday.
“One of the traps was wood with nails in it that had been dug in the ground and had leaves over it.”
He added: “We all wear helmets, but not all of us wear body armour. If one of us fell off our bikes these traps could cause serious injury.
“I have reported it to the National Trust and they have referred it on to the police. I think they have been put up by someone who doesn’t want bikes on the track.” Earlier this week National Trust chiefs said that the track is being closed because of the “damage” it has caused to the area,
It says that, since opening in 2013, the track has been heavily used but has also led to increasing damage to the surrounding woodland.
The National Trust says the track has not been closed as a result of traps, but a pre-existing arrangement with Natural England.
A Trust spokeswoman said: “Although the recent images of what has been going on at Penshaw track are very serious and we do not condone it at all, there were already plans to close the track due to our crucial partnership with Natural England. “As a conservation charity, we have an obligation to protect these special places.
“After a few failed attempts we have managed to speak to the cyclists, which is excellent. “As an organisation who encourages people into the outdoors and understands how important sport is, we would really like to support the cyclists in finding another location for the track in the area.
“We would like to find a solution so the group have somewhere safe to go and enjoy sport.”
A Northumbria Police spokeswoman said: “We are aware of the concerns that have been raised.”