MONTREAL — The federal government released a long-awaited report Wednesday on Montreal's deteriorating Champlain Bridge, completing a swift 24-hour about-face.

The state of the deteriorating, federally managed bridge has been a source of public concern in the Montreal area since the release this spring of another report that warned it's at risk of collapse.

The latest report says it would cost as much as $25 million per year over the next decade simply to prolong the life of the bridge -- and that still wouldn't produce a long-term fix.

The document released Wednesday, the result of a study by a consortium of engineering firms, referred to previous assessments that the bridge could be knocked down by a powerful earthquake.

"Annual expenditures rising from $18 million to $25 million over the next ten years, increasing at a constant rate, would be necessary to prolong its life, without in any way improving the level of seismic performance or rehabilitating the bridge deck," said the report.

"The maintenance work will become increasingly extensive and complex and require increasingly long lane closures and ever greater inconvenience for users."

The study's release comes just one day after the Conservative government said it would not make it public.

The federal transport minister, Denis Lebel, said Tuesday he didn't want people to worry unnecessarily.

But the minister's comments had the exact opposite effect; the Champlain Bridge immediately became a top news story in Quebec and his remarks fed local concern about how safe the heavily used span is.

The summary of the report released Wednesday, which is dated from March, does not delve into the safety concerns with the existing span.

It does examine several replacement options for the 49-year-old bridge, one of Canada's busiest spans.

It concludes that digging a tunnel would include numerous benefits, but would also cost more than a new bridge.

The report estimates the cost of a replacement bridge (including the $155-million demolition of the existing span) at $1.3 billion, while a new tunnel would cost around $1.9 billion.

On Tuesday, Lebel said the actual work that will be done on the bridge, which is crossed by some 60 million vehicles annually, is more important than the content of any report.

He said people without the proper expertise might misinterpret the report's findings and cause people to worry for nothing.

He also said he was concerned that some people might try turning the Champlain Bridge into a political issue.

But the Prime Minister's Office announced Wednesday morning that it would lift the veil of secrecy on this document.

Just before releasing the report, a spokeswoman for Lebel rejected the suggestion that the government had a change of heart. Spokeswoman Vanessa Schneider said it was a simple question of timing: Lebel was only appointed to his job in late May.

Later in the day Lebel himself issued a statement: "We want to ensure that Canadians have access to information about the Champlain bridge, and that is why the pre-feasibility technical report has been publicly released," he said.

As for replacing the bridge, he added that, "all options are being considered and remain on the table."

Another structural assessment of the bridge, released in March, warned that the six-kilometre-long Champlain was at risk of falling into the St. Lawrence River.

"It has been recognized there is a risk of partial collapse of the bridge, or even the collapse of a span," said that report, which was prepared for the federal agency that maintains the bridge.

Even the Roman Catholic Church in Montreal recently made use of public fears over the condition of the bridge.

The archdiocese of Montreal used a cheeky highway billboard as part of its annual Easter fundraising campaign.

The roadside advertisement advised motorists to, "Say Your Prayers," as they approached the crumbling structure.