A Government-backed scheme to stimulate competition in one of the most concentrated areas of the banking sector is being launched prematurely in order for ministers to claim that they are helping consumers, the industry is warning.
Sky News understands that an online current account tool that will enable consumers to compare the suitability of banks' products based on their transaction history will be far more limited than ministers had demanded when it goes live in the next few weeks.
Under an agreement announced a year ago, the UK's biggest current account providers, including Barclays (LSE: BARC.L - news) , Lloyds Banking Group and Santander UK, have committed to participating in the MiData scheme, which could launch later this month.
However, it will get under way without a component that observers say will be critical to its effectiveness.
The British Bankers' Association is understood to be co-ordinating the involvement of the major high street lenders.
In the Autumn Statement in December, George Osborne said the price comparison site GoCompare would launch a current account tool under the MiData brand on April 1 this year.
Industry sources said, however, that the absence of a technical feature called Application Programming Interfaces (APIs) would make the service "clunky" and far more difficult for consumers to compare current accounts in a market featuring scores of complex products.
Bank customers will be forced to download their transaction data and then submit it to GoCompare in a process that experts say is likely to deter many people from using the service.
It will also be unavailable on mobile or tablet devices during the initial phase of its operation, the sources added.
The Treasury, which is expected to outline further details of the MiData current account launch in Wednesday's Budget, has set up a working group to look at APIs, the use of which would make information comparison much simpler.
The Chancellor hailed the initiative a year ago as "a major breakthrough in empowering consumers and increasing competition in high street banking".
"MiData, combined with seven-day account-switching, means that the Government is arming customers with the weapons they need to hold banks to account to make sure that they are getting the best deal," Mr Osborne added.
However, senior bankers said the scheme was "undoubtedly" being launched before it was ready.
"There will be big teething problems," said one.
The Treasury also announced last March that Martin Lewis, the founder of MoneySavingExpert.com and one of the UK's most prominent consumer campaigners, would develop a comparison tool for current accounts.
However, Mr Lewis told Sky News that the progress to date had not been sufficient to justify his involvement.
"I think MiData is a wonderful opportunity but until we get agreement from banks to provide an easy interface to provide the data it is never going to be a mainstream tool for consumers.
"We hope it will fully come together within the next year or so. This announcement is likely a bit of a PR stunt to claim credit for the move before the general election."
Some consumer groups have also raised concerns about the effective protection of customer data within the MiData initiative, which has also encompassed energy companies and credit-scoring firms since its launch in 2011.
Last week, the City watchdog said that the seven-day current account switching service (CASS) was working effectively for consumers who had used it.
The Financial Conduct Authority (FCA) said, however, that there was insufficient awareness of CASS's existence, and suggested that full current account number portability would make it likelier that many consumers and small businesses would change providers.
The banking industry has argued that full portability would cost billions of pounds and that it has already taken significant steps to improve competition.
The BBA declined to comment.