"PostFinance has ended its business relationship with Wikileaks founder Julian Paul Assange," the bank said in a statement issued in Bern.
"The Australian citizen provided false information regarding his place of residence during the account opening process. Assange entered Geneva as his domicile. Upon inspection, this information was found to be incorrect. Assange cannot provide proof of residence in Switzerland and thus does not meet the criteria for a customer relationship with PostFinance."
WikiLeaks responded with a Twitter message calling Assange a "homeless refugee," The New York Times reported.
It said the account held 31,000 euros (about $41,300) and the bank's move revealed "the power dynamics between supposedly independent states like Switzerland, Sweden and Australia."
Sweden is pursuing Assange on sex charges.
On Sunday the American ambassador to Switzerland, Donald Beyer, told the magazine NZZ am Sonntag the country "should very carefully consider whether to provide shelter to someone who is on the run from the law."
Last week, WikiLeaks released classified cables from a cache of U.S. State Department documents it had obtained.