Treasury Board President Scott Brison has tabled legislation in the House of Commons to repeal controversial Conservative changes to the sick leave program for federal public servants, a move that will add $900 million to the government's mounting budget deficit.

But the Liberal government said reversing the change is not an endorsement of the status quo, and Brison said he will still push to "modernize" sick benefits for bureaucrats.

"Repealing what the Conservatives did was the right thing to do," Brison told reporters when asked about the latest move to reverse legislation enacted by the last government. "What the Conservatives did disrespected the negotiating process. It was irresponsible and unfair.

"It set the wrong tone and sullied the negotiating environment with the public service unions. We've always been clear we're going to negotiate in good faith … and we will seek to modernize sick leave benefits with the public servants in a way that is fair."

The legislation comes at a crucial time as Brison returned to the bargaining table with the Public Service Alliance of Canada (PSAC) this week — the largest of the 17 unions representing public servants — to hammer out a new collective bargaining agreement. Relations are expected to be less frosty with the sick leave changes off the table.

Treasury Board President Scott Brison says he looks forward to "constructive" negotiations with public service unions. He said he hopes to "modernize sick leave" as part of the process. 4:59

Tories had already booked savings

The Conservatives unilaterally amended the Public Service Labour Relations Act last spring to replace the long-standing sick leave program, a move that angered public service unions who said it was a violation of their collective bargaining rights.

Clement made the proposed changes in an effort to get away from the practice of "banking" unused sick days for use at a later date.

He sought to replace that system with a less costly short-term disability benefits program and to reduce the number of sick days from 15 to six, which would expire at the end of the fiscal year if unused.

The program has yet to be changed, but former treasury board president Tony Clement had already booked a savings of $900 million in the last budget — a figure he called "sacrosanct" — by far the largest line item savings for the Conservative government in its push to get to a balanced budget before the last federal election.

Because the presumptive savings were already documented in the last Tory budget, before the sick pay program had even changed, the Liberals will now have to account for the $900 million.

PSAC has challenged the $900 million savings figure, arguing that sick leave banks are not nearly the financial liability the former Conservative government claimed.

Former treasury board president Tony Clement unilaterally altered sick leave benefits for federal public servants, banking $900 million in savings for the Conservative government's last budget. (Adrian Wyld/Canadian Press)

Interim Conservative Leader Rona Ambrose slammed the latest Liberal move, saying that the reversal would be a costly mistake for a government already facing a fiscal crunch.

"I think it's unfortunate because those measures were agreed upon between the [Tory] government and the union," Ambrose said Wednesday.

Public service unions have, however, objected to the changes since they were first announced.

"There was a great deal of concern around how those leave provisions were used. This will cost taxpayers $900 million a year to repeal this piece of legislation. I'm not sure if that was included in the $10-billion deficit pledge; I doubt it. The costs of this government just continue to escalate," she said.