Coober Pedy's only bank has been shut until next week, leaving vulnerable residents who do not use debit or credit cards unable to easily access their money.

The Westpac branch on Hutchison Street in the isolated opal mining town simply had a note on the door explaining it would be closed until Thursday, locals said.

Coober Pedy woman Julie Hammermeister said some locals, who did not want to use the town's ATM, were unable to buy food for themselves.

"They go into the bank to access their money, because a lot of people get humbugged [by someone demanding money] if they stand at the EFTPOS machine."

'Not the first time it's happened'

Fellow local Carrie Adamo said the closure had caused "a great deal of stress".

"It's going to impact on people's day-to-day spending with just food and refuelling their car et cetera," she said.

"Many ... Indigenous people prefer old-style banking because it's safer — they are able to control their money without their cards being used in the [ATM] by other people."

She said there was a funeral at Indulkana on the APY Lands that could not go ahead because attendees could not access money for transport.

"A lot of people here don't have access to online, and maybe their only outing for the day is to grab their cash and go to the supermarket," Ms Hammermeister said.

The bank usually opened Mondays, Tuesdays, Thursdays and Fridays for four hours a day.

The ABC has contacted Westpac for comment.