Toronto councillors shouldn't back a bid to host the World Expo in 2025, a report from city staff says.

The report, released Friday, suggests the risks of hosting the major international event at the city's developing Port Lands area outweigh the positives, which include a $3.3 billion boost to the city's gross domestic product and an expected $3.2 billion in tourism money coming into the city.

Several current and former councillors are backing a plan to bid on the Expo, suggesting the six-month long showcase of trade, innovation and products from around the world would be a boon to the city. Mayor John Tory, meanwhile, has been lukewarm about the project, suggesting he's concerned about how much the event would cost the city.

The city staff report highlights several serious concerns about the Expo 2025 bid, including:

The lack of clear provincial and federal support for hosting the event, pointing out that the federal government recently withdrew its membership with the group that runs World Expos.

The significant amount of money it would cost the city. Staff estimates hosting the event would cost between $6 and $7 billion.

Concerns that construction projects — including the East Bayfront light rail line — will be ready in time for the event.

A challenging construction schedule that could lead to cost overruns.

"Given these factors, the City cannot responsibly pursue a bid for the 2025 World Expo at this time without facing very significant financial, operational and reputational risks," the report says.

'They're scared,' councillor says as she rips findings

Coun. Kristyn Wong-Tam, a major supporter of the bid, said she's not surprised by staff's suggestion but is disappointed by it.

"What I read from the report is that they're scared. They're risk averse," Wong-Tam said.

She believes councillors should ignore the staff report and instead reiterate the city's interest in a bid dependent on other levels of government committing money to help develop the Port Lands area. Prime Minister Justin Trudeau, she said, has been clear that his government will explore potential funding if the city moves ahead with a bid.

Wong-Tam said there are several problems with not bidding on the event.

First, she said, it amounts to an insult to Toronto's construction industry. Second, it won't help the many companies and businesses based in the city that want a chance to shine on the world stage.

And finally, if Toronto doesn't seek out major federal funding, another city will — Wong-Tam suggests Calgary, which is mulling a 2026 Olympic Games bid, will be watching what Toronto does.

3 other cities in the running to host event

Toronto taxpayers, she said, have paid for major events all across the country. Now, she said, it's this city's turn.

If the city held the event, it could be the largest economic and cultural event held in Canada since Expo '67, the report notes.

Paris, Manchester and Osaka, Japan are also in the running to host the event.

Canada has hosted two world expositions, one in Montreal in 1967 and the second in Vancouver in 1986.