Durham Police probe councillor death threats
Labour politicians have been warned about their personal safety after death threats were made in a letter to Durham's chief constable.
The "highly politicised" letter named members of Durham County Council and was received by Mike Barton on 2 March.
The force said it had offered reassurance to those identified.
One councillor said the murder of Labour MP Jo Cox meant there was a "real threat" facing those who worked in politics.
A Durham Police spokeswoman said: "The letter contained a great deal of political rhetoric, along with threats to a large number of county councillors."
Councillor Carl Marshall, chairman of County Durham Labour, described the letter as "a threat to the democratic process".
He added: "Abusive correspondence is something that is sadly becoming increasingly common, but threats to the lives of Labour councillors is very concerning and not something that we have ever had to deal with.
"We have issued police guidance to all Labour councillors and prospective Labour candidates to be more aware of their own personal security and also to help in any way with the ongoing investigation.
"It would be easy to dismiss the threats contained in the letter, but the tragic murder of Labour MP Jo Cox serves to prove that there is a real threat facing those who work in politics, whatever party they represent."
The Durham force spokeswoman added: "Unfortunately, letters of this nature are not uncommon and are generally sent to cause concern to the recipients without any real substance behind them.
"However, inquiries are taking place to trace the person responsible for the letter and we are liaising with Durham County Council to offer reassurance to those named."