The federal government has pledged money for a subway extension in Toronto's east end, further muddying the waters on an already confused transit planning process.

The announcement included no information on the amount of funding or any conditions that may be attached. More details are expected Monday, setting the stage for another battle over where in Scarborough the transit line should run and raising questions about Ontario's plan to go it alone with a self-funded subway along a different route of its own choosing.

"[Finance Minister Jim Flaherty] and I, subject of course to the normal approvals process, have set aside funds to ensure the financing of Toronto's plan for the Scarborough subway extension," Mr. Harper said at what had been billed as a photo opportunity. "I think this is good news for Toronto commuters, who obviously continue to face the challenges of gridlock."

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He was joined by Mayor Rob Ford, a long-time proponent of subways, who was beaming as he left the event. Also on display was a map showing the route for a Scarborough extension that resembled the plan approved by city council this summer. The Ontario government prefers a different route.

"Pleased all levels of government – federal, provincial, municipal – are working together to build Council-approved transit for Toronto," Toronto Transit Commission chair Karen Stintz tweeted in response, adding later: "I applaud the Federal gov't for recognizing the importance of building the Scar. subway to Sheppard. TO needs a transit network."

But the announcement raises a number of questions, including whether Ottawa's contribution will amount to the $660-million council said it needed, when it backed the plan this summer, and whether this is new money or funds taken from another transit project.

There was no opportunity to ask these questions of Mr. Harper as reporters were kept out of the announcement. Followup inquiries to the Prime Minister's office, the mayor's press secretary and Mr. Flaherty's office were not answered.

Further complicating the issue, the provincial government said after the council vote that it had waited long enough and would move ahead unilaterally. The province's plan – to build a shorter subway extension along a different route than the one supported by council and now the federal government – is being studied by the TTC and a feasibility report is expected this week.

Provincial Transportation Minister Glen Murray has repeatedly castigated Ottawa's level of transit funding. In recent weeks, he has said that federal support for a Scarborough subway extension could allow it to go further. But he insists the route is firm.

"If other governments bring money to the table there is lots to invest in," Mr. Murray said Sunday evening in a series of text messages. "We have laid out our commitment to extend the subway from Kennedy to [Scarborough City Centre]. If some gov't wants to add to our commitment in Scarborough that is good news."

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But Mr. Harper's backing of council's route has effectively reignited the battle over whether municipal or provincial politicians are in charge of transit planning in Toronto.

Also, lurking behind all the transit posturing of recent months is a still-valid legal agreement to build light rail in Scarborough.

This contract was signed by the city, TTC and regional transit agency Metrolinx and most observers agree it can be changed only through mutual consent.

"The original LRT plan would serve thousands more Scarborough residents for far fewer dollars," said city Councillor Josh Matlow. "I hope that all three levels of government put reason before politics."