Peterborough residents may have to pay additional council tax to a new public body.
The Combined Authority for Cambridgeshire and Peterborough, which will be headed by an elected mayor, will have the power to levy council tax from April 2018.
Any money raised would be in addition to council tax given to Peterborough City Council - which goes up by five per cent next month - and the police and fire budgets.
Council leader Councillor John Holdich, who sits on the new combined authority, said: “There are no plans to levy council tax. I’m absolutely certain at this point in time we will not be voting for that unless there is something really special the public wants.
“I believe we can invest the money we have got from government in the right way and more than double it.”
The council tax precept is mentioned in newly released combined authority papers. But Cllr Holdich insisted that it had been discussed before the combined authority was agreed by councillors, with the Conservatives pushing it through with their majority.
A spokeswoman for the combined authority said: “The power of the mayor to introduce a precept was first included in papers in November 2016.”
This was the month councils agreed to introduce a mayor and combined authority.
The spokeswoman added that the mayor can introduce a council tax precept “if there is something he believes needs to have more money spent on it.” However, this would need the permission of both the Government and Parliament.
Liberal Democrat city councillor Darren Fower said: “This is the first I have heard of it. I think it’s very worrying - people are already stretched when it comes to paying council tax and this news could well mean they face an additional cost.
“And there will be some people out there who may ask is this all about funding the authority itself.”
The new authority will be led by the mayor from May. It includes the leaders of the seven biggest Cambridgeshire councils, as well as a representative from the Greater Cambridge Greater Peterborough Enterprise Partnership.
Together they will control a devolved transport budget and hundreds of millions of pounds to spend on housing and to boost growth.
The budget papers also state that the combined authority may be able to increase business rates to fund infrastructure in the future. But this is subject to Parliament passing new legislation.