The Phoenix pay system has been restored after a disruption in service that lasted several hours Tuesday morning and affected all federal government departments.

Public Service and Procurement Canada spokeswoman Anne Trépannier confirmed both the pay and pension systems were down for four hours, but are now "running normally."

Trépannier said there was a "storage space issue" on computers involved, because data was backed up during the weekend. She said Shared Services Canada identified the problem and began to address "immediately."

Wednesday is pay day for government workers.

In late July, the department said it had ended the practice of turning off the ability of employees to view their pay stubs in Phoenix a week before pay day.

The centralized payroll system was launched across the public service in April.

Public service unions warned the federal government not to go ahead with the full launch of the system and that it wouldn't be reliable.

In June, the government admitted 80,000 people had experienced some pay problems, including being underpaid, overpaid or not paid at all.

On Monday, Public Services and Procurement Minister Judy Foote was before a meeting of the government operations and estimates committee investigating problems with Phoenix.

She said the backlog had been reduced to 67,500 and it would be eliminated by Oct. 31.

Foote faced a grilling in question period Tuesday from NDP public services critic Erin Weir about the outage. The Saskatchewan MP said the minister is shirking her responsibility for the pay system's continued problems.

"The minister was very clear about one thing: It's not her fault, she tried to blame the previous government, her own officials and pay centre employees, anyone but her," Weir said of Foote's Monday committee appearance.

"And today the entire Phoenix pay system crashed. My question is simple: Whose fault is it this time? When will this minister take responsibility and when will she ensure all federal employees are properly paid?"

Foote said the government is "committed to a secure, reliable and modern IT system," and her focus is on making sure employees who work get paid for the work performed.

She also denied that she has placed any of the blame for this fiasco on staff.

"We're not blaming employees who are working hard on this file. We have employees who are working to make sure other employees get paid."