Federal public servants across the country will receive an apology from the minister of Public Services and Procurement Canada over the disastrous Phoenix pay system as the backlog of cases balloons to 520,000.

Carla Qualtrough says she wants government workers to know she cares, and is assuring them the Phoenix file is the most important one on her desk.

I am truly sorry that more than half of the public servants continue to experience some form of pay issue. - PSPC Minister Carla Qualtrough

"I am truly sorry that more than half of the public servants continue to experience some form of pay issue. Too many of you have been waiting too long for your pay," states the minister in her letter, which is dated Nov. 16, and is to be distributed to all federal public servants Thursday and Friday.

The backlog of cases includes 265,000 files in which public servants have been underpaid, overpaid or not paid at all, which the minister simply describes as "unacceptable" in the letter. Thousands more unresolved cases include administrative changes, such as missing direct deposit information.

Qualtrough's letter comes five days before an expected report from the Office of the Auditor General that will delve into the Phoenix pay problems, as well as the history of the system's development.

In her letter, Qualtrough promises her department will provide "detailed, regular, reporting on the measures being taken to address pay problems and stabilize the pay system in order to keep you better informed."

The letter makes no mention of a call this week by one of the country's largest civil service union to build an in-house pay system and to scrap Phoenix altogether.