More needs to be done to explain the benefits of devolution to regions like East Anglia and who will implement it, according to a report out today.
The study by the National Audit Office says the proposals do offer the chance to stimulate economic growth and reform local public services.
But it also suggests some of the most recent proposals, such as the one for Norfolk, Suffolk and Cambridgeshire, “set up more complex and untested arrangements.”
And it warns ministers must balance the benefits of its approach against the potential risks.
The report adds: “The arrangements are experimental and unlikely to work as intended in all areas and for all functions and services devolved.
“The government can do more to provide confidence that devolution deals can support economic growth and better value for money.”
Labour MP Meg Hillier, who chairs the House of Commons Public Accounts Committee, added: “Devolution does not absolve Government of accountability. As more money is devolved it is vital that there is clear tracking of where and how effectively it is spent.
“It is not enough to say the details are still taking shape. The big questions need to be answered, including who taxpayers can hold to account.”
The report comes amid growing hostility to the idea of a directly-elected mayor leading a new combined authority for Norfolk, Suffolk and Cambridgeshire, as set out in the draft devolution document for the region.
Last month, communities secretary Greg Clark insisted the mayor was a non-negotiable element of the deal, which the government says will give more than £1 billion of new investment to the counties, with a promise of further cash and powers in the future.
But several MPs and council leaders have urged the government to rethink the ideas, while some authorities, like Peterborough City Council, have put forward their own alternative proposals.