'Hardware issue' downs ATO digital services

The Australian Tax Office is struggling with an outage to its digital services, including its main website, after an unspecified "hardware issue" took the platform offline just after 9am on Monday.

Visitors to the ATO website are greeted with a message apologising for the outage.

"We’re investigating issues with online services, portals & our website as a priority. Apologies for inconvenience. Stay tuned for updates," the agency said on Twitter.

It is yet to provide details, but an ATO spokesperson confirmed the outage is extensive and pinned the blame on a "hardware issue".

The agency was unable to provide an estimated time for service restoration, but said it was allocating all available resources to the problem.

The tax office did, however, confirm the problems had not been caused by "any external factors".

It also emphasised that no personal taxpayer information had been compromised.

Update 5:30pm: The ATO advised that its online services would remain offline throughout the night while staff work on a fix.

"We'll update you again in the morning. Thanks for your patience," it said.

Update 9:30am 13/12/16: The agency said desipite 'wprking hard overnight' to resolve the issue, systems remained offline.

It said it hoped to bring services back online progressively throughout the day.