AMP is assessing the way data is handled after internal staff expenses details were accidentally stored in a public cloud service by a third-party contractor.

The breach was “quickly corrected” when the group became aware of it, a spokesman says.

“AMP treats data security very seriously and has strict policies in place regarding the handling of data with third party vendors. We are reviewing the situation to ensure standards are maintained.”

The group has not provided details on the extent of the breach, but media reports say more than 25,000 of its staff expenses claims were leaked.

The data breach also affected utility provider UGL, the Department of Finance, the Australian Electoral Commission and the National Disability Insurance Agency.