Mayor Stephen Mandel doesn't believe the federal government when they say pricey security costs were the reason they couldn't support Edmonton's bid to host Expo 2017. Mandel goes as far to say that the government "made this excuse up."

It's been one day since Mandel found out the feds would not support the city's bid to host the 2017 World Expo and he his anger hasn't subsided.

Local MP Rona Ambrose is speaking out after Mandel accused her of being the one responsible for the feds' support being scrapped for the city's bid.

She has defended the government's decision saying security costs would have added hundreds of millions of dollars to Ottawa's chunk of the bill.

"We can not afford this kind of an expenditure at this time," she said. "We've seen what happened with G8, G20 and we've seen what happened with the Olympics," she added.

But correspondence from earlier this month between local and federal officials obtained by CTV News suggests something different. It reads: "Officials at public safety believe the $10.9 million dollar estimate is accurate for federal security agencies."

But Ambrose continues to insist the security of oilsands facilities would cause the bill to escalate.

"While they may be legitimate security costs, they are very, very expensive and they could've eclipsed up to a billion dollars," she said.

The mayor isn't buying it.

"That's B.S., I'm sorry."

Alberta's Minister of Labour Thomas Lukaszuk agrees with Mandel.

"Our oilsands are secure everyday. There are terrorism risk assessments done on an ongoing basis and we are satisfied that they are secure," he said.

And while Mandel has pointed the finger at local MPs he believes the final word was given to the prime minister.

"In this government my assumption is that the prime minister makes all the decisions... it would have been his decision."

The city and province have already spent $3.5 million on the bid. The mayor said he will send a bill to the federal government, but it's not clear if the feds will pay it.

With files from Bill Fortier