Around-the-clock contract talks between the City of Toronto and the union representing its outside workers have resulted in a tentative deal.

Speaking at a news conference Sunday, CUPE Local 416 President Mark Ferguson characterized the negotiations as "probably one of the toughest" in Canadian history.

"We did it through tireless work," he told reporters. "We did have to give in a number of different areas just as we said we would."

He added that the two parties will be returning to the table at 9 a.m. on Monday morning to hammer out further details.

Details of the agreement won't be released until both parties hold a ratification vote.

Ferguson's union represents more than 6,000 outside workers including garbage collectors, paramedics, social housing workers, animal control officers and more.

Discussions between the two parties had spilled into the morning after stretching past a midnight and an extended 2 a.m. deadline.

Ontario's Ministry of Labour had given negotiators until Sunday before the city could legally lock out unionized workers or the union could legally go on strike.

Earlier in the month, Ferguson had said that the union didn't want to go on strike. He warned that any work stoppage would come at the hands of city officials.

For his part, Mayor Rob Ford said he was happy that both sides were able to come to an agreement and expressed confidence that city council would approve the deal.

Deputy Mayor Doug Holyday praised the hard-won but fragile agreement in a statement issued Sunday morning, calling it fair for city workers and affordable for taxpayers.

"We will be better positioned to deliver efficient services to the residents and businesses of Toronto," he said in the release.

Both Ferguson and Holyday thanked their bargaining teams for helping them come to a tentative settlement.

Throughout the negotiations, Ferguson has painted the city as a party that didn't want to bargain fairly or reach a compromise.

When Holyday and his team tabled a proposal last Thursday, Ferguson accused the city of trying to provoke the union into a fight.

However, the union president did something of an about-face on Sunday, telling reporters "they did want to get to a deal after all."

Thursday's proposal included a 1.25 per cent lump sum wage payment in 2012, a 1.5 per cent lump sum payment in 2013, a 1.75 per cent lump sum payment in 2014, and a 1.75 per cent base wage increase in 2015.

It also nixed the city's controversial "work-for-life" guarantee.

City and union officials haven't lifted the lid on Sunday's tentative deal yet, but Ferguson said concessions had been made.

Over the next 48 hours, the City of Toronto and CUPE Local 416 members are expected to finish polishing off the agreement before proposing it for ratification.

A strike or lockout situation could have affected city snow removal, garbage collection, animal rescue, road maintenance and other services.

City officials say negotiations with their inside workers, represented by CUPE Local 79, are still ongoing.