Toronto Mayor John Tory on Sunday said he has "significant concerns" for the city as Canada moves toward cannabis legalization this week, prompting him to write to Ontario's attorney general to affirm support from the province.

"I think there are many, many things that are going to confront us that haven't confronted us before," Tory told reporters about the weeks and months following legalization on Oct. 17.

"I think we can deal with them, but we need time and we need co-operation between governments."

In a correspondence to Attorney General Caroline Mulroney, Tory said his support for cannabis legalization has always been partly contingent upon assurances from the province that Toronto "isn't unfairly burdened with increased enforcement and social costs triggered by this significant change."

We're going to get more phone calls from people saying, 'My next door neighbour is smoking marijuana. What are you going to do about it?' - Toronto Mayor John Tory

He added, "There will be increased costs borne by the City of Toronto, and those costs will be disproportionate to other cities in the province. On that point, I hope there is no dispute."

When asked about what kind of problems he foresees in the wake of legalization, Tory said that there's been reports of people "going down the sidewalk smoking marijuana," adding that he expects to see more of that happening.

While there is nothing illegal about that under the incoming laws, Tory said that city resources could be strained by residents unaware of the details of legalization.

"We're going to get more phone calls from people saying, 'My next door neighbour is smoking marijuana. What are you going to do about it? And the answer is — under the law — not very much. But we have to get used to those kinds of things," Tory said.

In his letter to Mulroney, Tory said he plans to collect data from relevant city agencies, such as the police and the licensing and standards department, to help get a better idea of how the city adjusts to the new reality of legalized recreational cannabis.

He said the data will be shared with the province and federal government.

Mayor's letter welcome: attorney general

In a statement to CBC Toronto, Mulroney responded to the letter and said that the province is ready with a plan to keep communities safe and take on the illegal market.

"The Mayor's letter and his commitment to sharing information and insights are welcome, and we will continue to work with all levels of government to properly address the social and health risks associated with the sale and consumption of cannabis," she said.

"Additionally, Ontario has pledged $40 million to help assist municipalities with costs associated with the federal government's legalization of cannabis."