Derbyshire County Council challenges Chesterfield-Sheffield link-up
A proposal to allow a new Sheffield regional mayor to oversee some services in a nearby Derbyshire town is being opposed by the county council.
Derbyshire County Council leader Anne Western says she will seek a judicial review of the plans to give Sheffield control of transport services.
She said the move would cost the county "millions of pounds".
A Sheffield City Region spokesman urged residents to take part in its consultation into the proposals.
The plan calls for Sheffield City Region's new mayor, who will be elected in 2017, to take responsibility for major roads, public transport, skills for employment and major planning and investment projects.
Mrs Western said: "Chesterfield is Derbyshire's biggest town, most people who live there also work in Derbyshire and they don't want to become a suburb of Sheffield − which is effectively what will happen if these plans go ahead.
"We need to act now and send out a strong message to help put a stop to these proposals or risk Chesterfield spending the next 30 years living in South Yorkshire's shadow."
A county council online poll on the proposal had 4,000 responses with 92% against, she said.
Chesterfield council leader John Burrows, who supports the move, said the new plan would result in "more than £18m worth of investment into development in the town and consideration for all the new investments coming forward".
He also said the money spent on the legal challenge by the county was "the wrong thing to do".
Mrs Western said: "I know we'll be criticised for taking this action by some who claim it's not the best use of money.
"But the fact is that if Chesterfield becomes a full member of Sheffield City Region it will undoubtedly be at a huge financial cost to Derbyshire County Council."
Sheffield's public consultation on the proposal closes on 12 August.