Toronto Mayor David Miller is outraged after learning the province has effectively scrapped the city's public transit expansion plans.

In Thursday's budget the Ontario government said it was postponing delivery of $4 billion to the Metrolinx regional transit agency - which is in the process of building more than $9 billion worth of public transit projects in the GTA.

Miller called the move "thoughtless," "disgraceful" and said he was "beyond disappointed" with the provincial government's decision.

Most likely to be shelved will be large sections of Toronto's Transit City project which was supposed to build light rail lines from the fringes of the city into the centre.

In an interview with CBC News after learning the details of the budget, Miller was livid.

"It's beyond disappointing. It's an astonishing betrayal of the commitments this government made to the people of this city."

"The Transit City program in Toronto connects neighbourhoods where people have the least - neighbourhoods where people work two and three jobs just to put food on the table. This provincial budget threatens all of that," he said.

Miller said the province is backing out of a promise it has made many times.

"On at least four occasions I had the privilege of standing beside Premier Dalton McGuinty when he promised over $8 billion dollars of investment in this city," said Miller "Why would you take that investment away?"

Ontario Finance Minister Dwight Duncan's budget delays the delivery of about $4 billion in transit funding for five years as the province wrestles with a deficit of more than $21 billion.

Although transit officials have not released any detailed assessment of what the result of the funding delay will be, it's believed that some of the ambitious light rail plans Miller envisioned for areas of Scarborough, Etobicoke and other northern areas of the city will be put on hold.

The LRTs along Finch Avenue West, and Sheppard Avenue East, as well as the Scarborough RT and the cross-city Eglinton line are in doubt. It's believed the expansion of the Viva bus service in York region will also be affected.

Duncan said his government was faced with - and had to make - some hard decisions.

The finance minister told CBC News on Friday morning that the projects weren't being cut - just delayed by "changes to the schedule of implementation."

"We didn't cut them. We're proceeding with them," Duncan said. "It's going to take a little longer than we hoped."

He promised the transit expansions promised for the Toronto Pan Am Games in 2015 will be finished on time, including the Union-Pearson GO Transit line.

The Sheppard Avenue light rail line and the York University subway line are expected to proceed on schedule.