The new MasterCard 'unique' card, developed in association with Advanced Payment Solutions, works in the same way as a mobile phone top-up card and is aimed at people who have just moved to the UK or do not have access to basic banking facilities. Employers can pay salaries onto the pre-paid Chip and PIN card and account holders can re-load it at over 14,000 Post Offices throughout the UK.

MasterCard says that more than 400,000 new workers have entered the UK over the last two years and find opening a bank account with no national insurance number, no credit history and no guaranteed employment "almost impossible".

High street bank HSBC has hit out at the claims, arguing that its new 'passport' account - which can be opened in advance of moving to the UK - offers more to migrants than prepaid cards. Passport offers a current account with Maestro International debit card, fee-free cash withdrawals from ATMs in the UK, a Flexible Saver Account and access to telephone and Internet banking, standing orders and direct debits as well as discounted Priority Payments for international remittance payments back home.

Joe Garner, head of UK personal financial services at HSBC, says: "Traditionally, opening a bank account has been one of the most trying aspects of setting up home for the first time in the UK. Passport is a relocation service that provides the essentials to make the move as smooth and straightforward as possible, and the positive response to the account from new arrivals to the UK has exceeded our expectations."

Halifax, the UK's biggest provider of social bank accounts, has also entered the fray, arguing that new pre-pay cards aimed at people without bank accounts just don't add up. The banks says the cards have limited functionality and charge their holders regular fees they can avoid by taking out a basic bank account, such as Halifax's Easycash account.

No money is required to open an Easycash account, says the bank, and no credit scoring is carried out.

Paul Marriott-Clarke, head of banking at Halifax and Bank of Scotland comments: "Pre-pay cards may seem like the answer for someone without a bank account but they can be very costly even for just a few basic transactions every month. A basic bank account, such as Easycash, is by far the better option for those who have struggled to get a bank account previously. They are free, have more facilities and offer greater protection against losses. They add up to a much better deal than a pre-pay card."