The ongoing dispute about planned changes to Montreal police pensions took a new turn overnight Friday when more than 100 officers chose to call in sick simultaneously.

The province's labour relations board had to call an emergency meeting with the police union when they caught wind of the plan. The talks between the board and the Montreal Police Brotherhood union began at 2 a.m. and ran until 6 a.m.

The board declared the action illegal and ordered all the officers back to work. But many stayed home regardless.

The Police Brotherhood denied encouraging its members to call in sick. Montreal Mayor Denis Coderre called this latest pressure tactic unacceptable.

"I've been in politics for 30 years. They can yell at me, they can boo me, they can talk against issues, that's democracy. We can have those kinds of discussions. But if they're using some tactics that will have a direct impact on the citizens, there will be consequences," he told CTV Montreal.

Montreal police say that despite the high number of officers who called in sick, they were able to ensure that the usual number of officers were out on the streets. But they say they had to call in several officers to work overtime to make it happen.

Coderre says it will be the police union who will have to pay for all that overtime.

The officers are angry about Bill 3, which would see municipal workers begin contributing 50 per cent of their pensions. Montreal police officers currently contribute 24 per cent. Other municipal workers such as firefighters and bus drivers have also spoken out loudly against Bill 3.

Earlier this month, police officers chose to protest the bill by wearing red ball caps and "non-standard issue trousers," such as camouflage pants, while on the job.

The province says the current system is not sustainable because the municipal pension plan is already running a $3.9-billion deficit. Municipal Affairs Minister Pierre Moreau has said that Bill 3 will bring balance.

The bill enters public hearings at the end of August.

With a report from CTV Montreal's Kevin Gallagher