Three horses which have been left to illegally graze on common land could end up costing a town council up to £9,000 to remove.

Barnham Cross Common, in Thetford, is a Site of Special Scientific Interest and is currently undergoing a 10-year conservation project to promote native plant species.

The horses were left at the site on Monday, May 8 and Thetford Town Council - who owns the common - are appealing to the horses' owner to remove them from the land by 9am on Thursday.

A special full council meeting will take place tomorrow at 5.30pm and councillors will discuss the authority's options if the animals remain unclaimed.

An equine bailiff has been consulted and the council will have the option of selling the horses, rehoming them via a charity or horse sanctuary, or having them humanely destroyed.

Roz Barnett, amenities, land and property officer at the council, said: 'The council are really hoping that the owner of the horses removes them within the time scale given. Councillors will be considering whether to take legal ownership of the horses and having them microchipped and passports arranged so we can sell them - which will go against the costs.'

The cost of removing the horses, including handlers and transport, veterinary checks, microchips and passports, livery and rehoming or humane destruction, could cost the council close to £9,000.

Although public grazing was previously allowed at the site it was found to be detrimental to the growth of the natural plants and wildlife. The last grazing license was issued in 2002 but there have been spates of illegal grazing.

The council's conservation project, in partnership with Natural England, has seen tree felling and the clearing of invasive scrub at the common.

From Monday grazing animals will be introduced to help maintain the area's natural habitat.

Many endangered plants can be found within the common including prostate perennial knawel and tower mustard. More than 60 bird species call the site home and managing the grassland will also help to attract and re-establish ground nesting birds such as woodlarks and nightjar.

If anyone has any information about the horse owners they are asked to contact Thetford Town Council on 01842 754247.