POLICE are investigating abusive and threatening letters sent to North Yorkshire councillors and council officers involved in the controversial plans for a £900 million waste incinerator.

Detectives said they were taking the matter extremely seriously, as the tone and content of the letters were “alarming”, and appealed for information from the public.

News of the probe came as North Yorkshire County Council met today to decide whether to press ahead with the incinerator at Allerton Quarry, between York and Knaresborough.

The authority’s executive has recommended councillors to award a contract for building the huge plant near the A1(M) to Spanish firm Amey Cespa.

City of York Council has already approved the proposals, despite fierce opposition.

Opponents claimed possible alternatives to the plant have not been examined and raising concerns about the potential £1.4 billion combined cost to the two councils.

A county council spokesman said senior officers and councillors had received “abusive and threatening” emails in relation to the incinerator plans, and the matter had been passed to North Yorkshire Police.

He did not reveal what threats were made, or which councillors or officers had received the emails.

Detective Inspector Heather Pearson, of Harrogate CID, said: “We are taking this matter very seriously.

“The tone and content of the letters is alarming.

“The incinerator is an emotive issue, but those opposed to any decision must realise that they cannot break the law and threaten the safety of people going about their work.

“I would like to appeal to anyone who has any information about the matter to contact the police immediately.”

Police said anyone with any information should phone Harrogate CID on 0845 60 60 247 or give information anonymously to Crimestoppers by phoning 0800 555 111.