Plans to introduce a £20 million computerised smartcard payment system for West Midlands bus passengers should be put on hold for the forseeable future, according to the politician responsible for overseeing the initiative.

Len Clark, the lead member for buses on the Passenger Transport Authority, said there was no business case for the smartcards and he feared the system would put additional costs on to council tax bills.

His comments came after a WMPTA scrutiny committee highlighted a number of difficulties with smartcards, which Centro wants to introduce across the region in 2007.

T he committee report pointed out that there is currently no manufacturer able to provide the "off the shelf" technology needed to scan the cards of passengers as they get on and off buses.

The report also conceded that the scheme would not warrant a business case that would attract Government funding and there could be significant costs to the public sector. The only source of funding would be through borrowing by the seven West Midlands Councils.

Coun Clark (Con Birmingham Quinton) said: "In principle, the introduction of smart card system is to be welcomed but sorting out the fundamentals is a prerequisite to committing any public money. Centro haven't done that.

"At the moment we haven't even designed a system that meets the legal and technical requirements and the cost requirements.

"Until we have agreement with the operators to introduce a model that works we ought to be cautious and not be making grand public statements that we cannot deliver on.

"We should not be introducing smartcards simply because it is a good idea. We have to have a business case and we haven't got one."

Coun Clark claimed that Labour councillors were attempting to steamroller the issue through the Passenger Transport Authority.

Coun Clark said: "This is part of the cost of having a coalition running the PTA. Labour want smartcards as soon as possible but the Conservatives are much more circumspect.

"My fear is that the costs will spiral and that the system will not make buses more attractive for passengers.

"In fact, it may have the opposite effect since most buses have single entrances and it would be difficult for people getting on and off at the same time to be scanned.

"It would lengthen journey times because the buses would have to stop longer," Mr Clark added.

A Centro spokesman said: "We are looking at funding options which will then be presented for members to decide the best way forward."