Telstra has apologised to thousands of Australians who had their details published accidentally online by the communications giant.

The company said the release of the names, numbers and addresses of some unlisted customers was not the result of any malicious cyber attack and was a mistake.

“For the customers impacted we understand this is an unacceptable breach of your trust,” Telstra executive Michael Ackland said in a post released online.

“We’re sorry it occurred, and we know we have let you down.”