Analysts believe there could be £400m lying in dormant accounts
A new website will let consumers reclaim money that has been sitting in dormant or abandoned bank accounts, before it is seized by the government.
The announcement follows the publication of the Dormant Accounts bill, under which unclaimed cash will be used to fund community projects.
The website aims to reassure customers they will still be able to access their money under the new system.
Analysts believe there could be £400m languishing in forgotten accounts.
The government hopes that the new bill will raise hundreds of millions of pounds for good causes.
In future the proceeds of bank and building society accounts where there has been no "customer-initiated" activity for 15 years will be reinvested by the government in a variety of community projects.
At the moment 80% of money left for that length of time remains unclaimed. However, the banks have launched the new website as part of a concerted industry effort to reunite customers with their cash.
Under the new system, a central reclaim fund will set aside a proportion of money received to meet the cost of potential future claims - including accumulated interest - before the balance transfers to the Treasury.
The new fund will be independent of the government and the banks, and will be regulated by the Financial Services Authority.
Angela Knight, chief executive of the British Bankers' Association (BBA), stressed that customers' rights would be protected.
"If you have money in an account it will always be your property, or if you die, it will become part of your estate," she said.
"This is the case no matter how many years pass," she added.
At the moment separate schemes trace customers' money in dormant bank, building society and National Savings accounts. They also cover outstanding premium bond prizes.
HOW TO RECLAIM NOW
Bank accounts: www.bba.org.uk or call 020 7216 8909
Building society accounts: www.bsa.org.uk or call 020 7437 0655
National Savings accounts and premium bonds: www.nsandi.com or call 0845 964 5000
All three have seen a surge in inquiries since the government confirmed it was moving ahead with its plans to take control of unused funds.
The BBA said its online tracing service received 98,000 hits during the three months to September, triggering 9,500 claims, more than for the whole of 2006.
The Building Societies Association and National Savings & Investments have also experienced unprecedented interest, with 130,000 visits to their equivalent web pages over the same period.
It is hoped that bringing the schemes together in a single internet-based service will encourage more people to claim, the banks said.
Halifax, Nationwide and the Yorkshire Building Society have already launched their own initiatives to reunite their customers with lost cash.
The integrated search is due to be launched in January 2008, while the government's unclaimed assets scheme is expected to begin in early 2009.