The union representing more than 750 City of London employees has put city hall on strike notice.

The inside workers' union has received an overwhelming strike mandate from its members following an impasse at the bargaining table.

No strike date has been set, but 91 per cent of the city's inside workers supported a strike mandate in a vote Thursday night.

It comes in response to what they say are deep concessions being sought by management.

Shelley Navarroli of CUPE Local 101 says, "There have been some very serious concessions put before us, and while some of them might have a monetary impact, it is not solely monetary."

Job action by the 760 employees would involve almost every municipal department and impact a wide range of services Londoners rely on.

They include social services, building inspections, business and marriage licences, bylaw enforcement and parks and recreation.

Deputy Mayor Paul Hubert was notified about the strike vote Friday.

"We don't want to go down that road, nor do I think the workers, even though there is a strike mandate."

Neither side is releasing details, but the stalemate is significant enough that the union wants the province to get involved in negotiations.

Navarroli says, "The union has requested the assistance of a conciliator from the ministry to come in and try reach a fair and equitable agreement."

There have been six meetings between the negotiating teams since the previous contract expired at the end of December.

Still, Hubert remains optimistic, "We all have to come together and find a way forward to these matters as we have done many many times before...We look forward to continuing to bargain and to come to a satisfactory agreement."

CUPE says no new negotiations are scheduled and they are waiting to hear back from the province about the conciliation process.

Both sides say they're still willing to talk, but with no contract and a strike mandate, labour unrest is a serious possibility.