Moves to change Warwick District Council's 01926 telephone code have been challenged by its Liberal Democrat group, which has asked the authority's scrutiny committee to take a closer look at the controversial idea.

The group says the 0845 prefix wanted by officials is a 'premium rate' number for many people.

And they say a change would hit the less affluent, who may need services most, the hardest.

For those with 'inclusive' call deals with companies like Sky or Virgin, or who use 'pay as you go' mobiles, 0845 calls could cost several pounds.

Officials want the switch so district and county councils can share a number, but a decision was delayed earlier this month amid heavy criticism.

Coun Bill Gifford (Lib Dem, Milverton) said then: "It doesn't make sense that the people who can least afford it are going to bear the brunt."

This week national campaigner David Hickson also entered the debate - questioning the decision not to opt for an 0300 code, which must be included in cheap deals.

He claims the decision is contrary to advice from Ofcom, the telecommunication regulator, and a government report.

Mr Hickson suspected the crux of the issue is that features such as call-holding and automation must be paid for by someone.

He says that if an 0845 number is used the caller pays for the extra facilities - and the council benefits from a reduction in the bill it pays to its phoneline provider. An 0300 code means the council pays for the automation.

Calling the choice of 0845 "sinister" he said: "In presenting its report, the council is perhaps keen to conceal that callers are subsiding it when calling 0845 numbers.

Councils should not be subsidising services by indirectly imposing premium charges, especially if this policy is not declared."

The matter will be discussed at a scrutiny and overview committee meeting at Leamington Town Hall on Tuesday, from 6pm.

Coun Alan Cockburn, Warwickshire County Council cabinet member for resources, denied the authorities stood to profit from 0845.

He stressed a variety of options were being considered and that "value for money and service to customers" were the key criteria.

He admitted costs could "vary between providers", but said: "Neither authority stands to generate any revenue from using an 0845 telephone number."

He added: "Mr Hickson presupposes the service provider would share revenue with the council, but this is an incorrect assumption.

"The provider will be selected on the value they offer customers. Callers will not be 'subsidising' the county council".

He said the authority's openness in publishing the entirety of its report were hardly the actions of anyone whose motives are 'sinister'."

A spokesman suggested 0300 "did not offer the best service for all customers".