The Ipswich town centre Barclays branch has been forced to close after leaking rain water damaged the bank's electric light fittings.
Customers were asked to leave the branch in Princes Street, near the Cornhill, after the safety hazard was discovered shortly after midday on Friday.
A spokesman for Barclays was unable to confirm when the bank would be able to reopen.
The spokesman added: "Due to the current weather conditions, our Princes Street, Ipswich branch has today experienced water leaking into the branch and through electric light fittings.
"For the safety of our customers and colleagues, we have had to temporarily close the branch until we are able to make the building safe.
"Colleagues are outside the branch and will be happy to answer any questions and advise on nearest branches. Our ATMs outside the branch continue to be operational.
"Both personal and business customers can also use the local Post Office to withdraw cash and pay in cheques. We apologise to our customers for any inconvenience this closure may cause, and we will work as quickly as we can to get the branch open again."
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