The account will suit people who do not have a lump sum to invest
Alliance & Leicester is to launch a regular savings account with a market-leading interest rate of 10%.
But internal documents passed to BBC Radio 4's Money Box programme about the Premier Regular Saver account show there are some catches.
The rate will last for only one year and will only be available to new customers who open a linked current account.
Anticipating complaints, the bank has produced a three page document for its staff on how to respond.
And in a statement, A&L defended the promotion saying the intention was to attract customers to its market-leading Premier current accounts.
It added: "Premier Direct customers enjoy a market-leading current account that pays a fantastic 5.00% AER credit interest rate, alongside the best overdraft rate in the UK at 5.9%."
Despite its drawbacks, Independent Financial Adviser Anna Bowes of Chase de Vere said: "It is a cracking rate, a fantastic rate, and hopefully it will encourage people to save."
Premier Regular Saver requires monthly savings, fixed up to a limit of £250.
Because of that the final return is not anywhere near the same as it would be if customers were able to invest the year's total savings as a lump sum when opening the account.
Customers will notice an overall gain of around 5% on the total amount paid in over the year, not 10%.
Existing A&L savers who opt for the account will be offered not 10% but 4.5% interest, and those who have had an account with the bank in the last three months will also not be eligible for the higher rate.
But Ms Bowes was not surprised by this.
"Loyalty is not always rewarded. It is all about the new customer. They are trying to encourage new people to come along," she said.
The bank was keen to point out that: "Existing customers already benefit from a number of special offers across our product range, including preferential rates and cashback.
"In addition, we have chosen to offer higher rates to our existing customers on key savings products this year.
"Our overall portfolio of products demonstrates the outstanding value we provide to new and existing customers."
The new account was scheduled for launch on 31 October, but on Friday A&L told the programme they may now bring it forward.
BBC Radio 4's Money Box was broadcast on Saturday, 22 October, 2005, at 1204 BST.
The programme was repeated on Sunday, 23 October, 2005, at 2102 BST.