Winnipeg city administrators are moving ahead with plans to remove overtime from pensionable income and compel police officers to work longer before receiving their pension benefits, an email sent to city councillors says.

Mike Ruta, the interim chief administrative officer, sent a letter to both the Winnipeg Police Association and the Winnipeg Police Senior Officers' Association, notifying the unions that city council will consider changes to the police pension plan.

This follows "many meetings and correspondence" about the issue with the two police unions since Oct. 21, 2016, Ruta said in an email to city council about the proposal.

The city could save $1.5 million annually by removing overtime from pensionable benefits and the extra funds could be reinvested in police operations, he said.

The Winnipeg Police Senior Officers' Association and the Winnipeg Police Association are gearing up to fight the city's plan.

"My reaction was one of shock actually," said Insp. Kelly Dennison, president of the Winnipeg Police Senior Officers' Association which has approximately 30 members. "Of course it's our opinion that they can't do this."

Both the Winnipeg Police Senior Officers' Association as well as the Winnipeg Police Association, which represents most Winnipeg police staff, argue the appropriate place to discuss pension benefits is around the bargaining table.

"It will be a significant legal battle that could be expensive for both parties, but we will take every action possible to prevent the city from making unilateral changes to a benefit that was previously negotiated," Moe Sabourin, president of the Winnipeg Police Association, said in a written statement to CBC.

Other proposed amendments include equal sharing of the cost of the plan, which would mean police officers would have to contribute more to their pension plans over time, and adjustments to early retirement provisions that would compel officers to work longer before receiving pension benefits, a subsequent email from Ruta said.

"Generally these proposed revisions are consistent with other similar pension plans," he said.

Council will likely see a report on the matter in fall.

Kalen Qually, a spokesperson for the city, said Wednesday an administrative report will accompany the proposal.

The report will outline "options to make the plan more sustainable and to bring it more in line with other municipal pension plans," said Qually.

If approved, the changes to the police pension plan could be in effect by 2020, according to Ruta.

All the proposals, which would require bylaw changes, need council approval.

Mayor Brian Bowman campaigned last year on removing overtime from police pensions.

"I obviously believe that changes are needed to look out for the long-term sustainability of the plan for the benefit of taxpayers as well as the members," Bowman told CBC reporter Bartley Kives in September.

Sabourin said he is meeting with Winnipeg police membership Thursday morning and evening and he'd be willing to comment in greater detail on the city's plan after that.

The current Winnipeg police collective agreements are set to expire in December 2021.