Councils across Norfolk and Suffolk are facing an unwelcome bill to upgrade their parking meters – because 5p and 10p coins are about to get thicker.

From January, the Treasury intends to mint coins using steel instead of copper and, while they will have the same weight and diameter, the coins will be 11pc thicker.

The new minting method will save the Treasury �176m, but dozens of local authorities which will have to foot the bill for updating its parking meters so they can accept the new coins. The Local Government Association (LGA) has called for the Treasury to pick up the tab for all the councils which need to change their machines.

Not all councils in the area charge for parking, but of those that do, the biggest bill to upgrade will be in Norwich, where 110 parking meters will need to be changed.

Some of those meters are owned by the city council and some by the county council and the estimated cost of upgrading them so they can take the new coins is �20,000.

Brenda Arthur, leader of Norwich City Council, said: 'I am totally in support of the LGA's campaign. If the government is imposing yet another cost on local councils, then they should foot the bill.'

West Norfolk Council said its machines will be able to take the new coins. North Norfolk District Council has had to reconfigure 22 of its machines at a cost of �4,224, while South Norfolk Council will have to pay �1,440 to update 18 machines.

Peter Box, chairman of the LGA's economy and transport board, said: 'Councils across the country are striving to continue providing vital services while managing deep funding cuts from government. The cost and effort of updating parking machines is an extra burden they could do without. This is cash which could be spent on filling pot-holes or concessionary bus travel.'

A Treasury spokesman said: 'The government consulted before deciding on the change, and the introduction of the new coins has already been delayed to allow industry – including local councils – time to prepare.'

dan.grimmer@archant.co.uk