The union that represents about 6,000 of Toronto's outside city workers says it has received a "very strong" strike mandate from its members.

A news release from Local 416 of the Canadian Union of Public Employees (CUPE) says its members turned out in "large numbers" in the past two days to give their bargaining committee approval to support a number of actions, including a work stoppage, should ongoing labour talks with the city fail.

"We are very gratified by what can only be described as a very strong vote for a strike mandate," said Matt Alloway, a member of the bargaining committee. "With this mandate, we are confident that we are in a position to negotiate an agreement that can strengthen the city's services by providing the workers who deliver those services with good, stable jobs."

CUPE leadership says it's concerned by the city's stance during negotiations so far.

"We are concerned that the city is choosing to take an aggressive approach to bargaining," said Alloway, "so it was an important time for us to engage with our members, update them on what is happening at the bargaining table, and gauge their support."

CUPE Local 79, representing 20,000 Toronto frontline workers, has already given its leaders a strike mandate

CUPE has asked the Ministry of Labour to appoint a conciliation officer to assist in its bargaining with the city.