Sheffield Council will fight one of its own elected members in court in an attempt to stop 'unlawful' protests against tree felling.
Coun Alison Teal will appear in front of a High Court judge in Leeds on Monday to defend herself against injunction proceedings launched by her own authority.
The Green Party member is one of nine people choosing to fight legal action in relation to the ongoing dispute about tree felling in Sheffield.
The council asked Coun Teal and others to sign an agreement saying they would no longer protest within safety barriers put up around trees due to be cut down.
Seven people have done so, but the rest have not and will appear in court next week.
Coun Teal, who represents the Nether Edge and Sharrow ward - where some of the most controversial felling is taking place - said she had asked the council for time to get legal advice and use mediation, but the court claim has now been issued.
Fellow Green councillor Douglas Johnson, a former Law Centre, worker said it was 'outrageous' that the council was seeking an injunction against one of its own members.
Coun Teal was one of several campaigners to be arrested while protesting tree felling, but no further action was taken.
The council is working with Amey to fell and replace 6,000 of Sheffield's 36,000 street trees. The authority says an extra 600 will also be planted.
Cabinet member for environment Bryan Lodge said the authority found itself in an 'unwanted' position where it had to protect taxpayers from 'potentially catastrophic financial consequences' as a result of delays to the Streets Ahead PFI contract with Amey.
“Those who have deliberately chosen to take the law into their own hands by trespassing into the safety barriers erected around tree works are preventing the council from carrying out its statutory highway duties and are causing major delays, not only to tree works, but also to work on roads, footpaths and lights across the city," he said.
"Furthermore, if this major investment is not completed by Christmas, then the council faces the risk of major financial losses within its PFI contract."
Coun Lodge said those who were stepping inside safety barriers to protest had ignored 'repeated warnings'. He accused those doing so of trespassing.
“This is no longer peaceful protest, as the trespassers claim, but a deliberate and unlawful attempt to prevent tree works as part of the wider Streets Ahead programme," Coun Lodge said.
"In addition, the programme has already been challenged by the protesters at the High Court and Court of Appeal and was found to be lawful on all occasions."
He added: "This is a last resort option for the council and not one we ever wanted to take. We’re hopeful the court will support our case."