OTTAWA -- The websites Canadians use to file their taxes online went down Monday and the Canada Revenue Agency isn't saying when the services will be back online.

A spokesman for the agency said there is a "computer hardware issue" and apologized for the cut in services.

He called the disruption "temporary" but couldn't say how long it would take to repair.

The spokesman said the CRA is working with Shared Services Canada, the federal government's centralized information technology shop, to do everything it can to get the sites restored.

Some Twitter users say the agency's services appear to have been down since last night.

Currently both the "My Account," "My Business Account" and "Represent a Client" are unavailable, along with online services to file income tax returns or change your address or direct deposit information.

Mobile apps are also down, the CRA said.

The services are used heavily at this time of year for Canadians filing their taxes.

The deadline to pay any taxes owing is April 30.