Toronto Mayor David Miller says the U.S. State Department over-reacted by issuing an "unnecessary" travel alert for the city during the G8/G20 Summit period.

"It is true that parts of downtown Toronto, the roads in and around the security zone and highways leading into and out of the city will see disruptions at varying times," Miller said. "But there are many other parts of downtown Toronto that will remain unaffected by the summit."

The U.S. warning was aimed at American expatriates and those considering travel to Toronto. It told them about the potential for large-scale protests during the G20 Summit and said the downtown core should be avoided.

"Previous G20 summits have drawn large numbers of protesters and activists, and a number of groups have announced plans to demonstrate throughout downtown Toronto," the travel alert said.

"Even demonstrations that are meant to be peaceful can become violent and unpredictable. You should avoid them if at all possible. Be alert and aware of your surroundings and pay attention to what the local news media has to say."

Toronto MP Olivia Chow criticized the advisory, citing its potential economic impact on businesses in the city.

"It's shocking that the U.S. is telling these people not to come to Toronto," she said. "We need the tourist dollars."

But David Jacobson, the U.S. ambassador to Canada, said there is nothing out of the ordinary about the advisory.

"We issue these things all the time for events like this," he said. "We always do it for G8s, G20s. We did it for the Olympics in Vancouver. We did it for the World Cup in South Africa."

The alert mentions that a security fence is being built to enclose the Metro Toronto Convention Centre, where the G20 leaders and their delegations will be meeting on June 26 and 27.

This will constrict traffic in the area, it said.

The department said it doesn't expect significant protest activity in Huntsville for the G8 Summit, which takes place on June 25-26. However, it does say there will be increased security presence in the area during the summit and its lead-up period.

U.S. citizens should expect increased passport and security checks when they try to enter Canada during the summit period, it said.

The travel alert expires on June 28.

Toronto Police Chief Bill Blair has said there will be 3,500 of his officers working on summit security, along with 1,600 others from elsewhere in Toronto. He put those policing costs at $122 million.

The RCMP will provide security for the inner zone.

The Canadian Forces' JTF 2, the secretive special forces unit, will also be on standby.

Premier Dalton McGuinty told reporters he's not worried about the alert, adding he'd only be concerned if he were a tourist looking for a hotel room during the summit period.

The G20 delegations are estimated to total about 30,000 people.

"We're only talking a few days. After that, it's still one of the best places in the world to visit," the premier said.

The Elephant and Castle pub at Yonge and Gerrard Streets is right next to the Delta Chelsea hotel. About half its business comes from American tourists. "It's going to hit us big-time," kitchen manager Kyle Underwood said about the alert.

However, one U.S. tourist doubted it will deter those Americans who know and love Toronto. "I don't think we would just stay away," said Oly Ruiz.

Boating restrictions

Add boating restrictions to the disruptions to vehicle and aircraft movement during the summit period.

There will be eight security zones in Toronto's harbour and at the ferry terminals where boaters will be restricted from entering. Some RCMP boats from Montreal arrived to help provide security.

Security personnel might be conducting spot checks of vessels on the water.

One water taxi operator is worried the additional security will cut into his business during the summit period.

"Who's going to come down and go through all that security just to go to the (Toronto Islands),