Ottawa Mayor Larry O'Brien says a prominent Ontario cabinet minister crossed the line when he questioned whether the proposed location for a downtown tunnel will put the federal government at risk in a post 9/11 world.

"Quite frankly, it's astounding that someone would take the lives of 3,500 people that died in 9/11 and throw that into this whole equation. Personally, I find it quite revolting, but we'll just move forward and sort of ignore that kind of chatter from the sideline," said O'Brien.

The mayor's comments come after Ontario Municipal Affairs Minister and former Ottawa mayor Jim Watson questioned whether the tunnel's close proximity to Parliament Hill will increase security risks for federal politicians and government employees.

Watson said there's no doubt the RCMP and officials in the Prime Minister's Office will be concerned about the tunnel's location.

However, O'Brien called Watson's reference to 9/11 unnecessary and "unbecoming of a minister of the Crown."

"Thankfully, for the city, he's really not the person who's going to make the choice," O'Brien told CTV Ottawa on Monday.

Budget expected next month

Meanwhile, city planners are advising residents that the budget for phase one of the project won't be released until late October.

Although one source says the cost for the initial phase of the project could spike 25 per cent higher than the original estimate, the mayor says it's premature to say the project is running over budget.

"There's no budget yet," O'Brien told CTV Ottawa.

The first phase of Ottawa's transit plan includes building a downtown tunnel, as well as constructing an east-west light rail line from Blair Road to Tunney's Pasture. The city's current estimate for the initial phase of the project is $1.8 billion.