The City of Toronto has, for the second time this month, reached an impasse in contract talks, this time with its largest union representing 23,000 inside workers.

The city requested Friday that the concilator request a "no-board" report from the province's Ministry of Labour, saying conciliation with CUPE Local 79 "has not worked so far."

The move is the last legal step before a possible work stoppage. If the request for a no-board is granted, it starts a 17-day countdown to a legal strike or lockout.

"We are continuing to bargain with Local 79 and remain hopeful that a resolution is possible during this 17-day period," Deputy Mayor Doug Holyday said in a news release Friday.

The city's signaling that negotiations are going nowhere comes a week after the Toronto Public Library's union announced that it had requested a “no-board” report from the Ministry of Labour.

The request was granted Thursday, meaning a library lockout or strike could legally begin on March 18 if no agreement is reached.