The $309-million rescue of the mostly vacant MaRS office tower is shaping up like the gas plants scandal with the Liberal government refusing to release documents, Progressive Conservatives said Monday.

Premier Kathleen Wynne came under fire as the legislature returned for its fall session with opposition parties pressing for the government’s $65-million bailout of a U.S.-based developer named Alexandria Real Estate and a $224-million loan to MaRS from Infrastructure Ontario made after a hasty rule change four years ago. Interest on that loan is costing taxpayers $450,000 a month.

“You obviously haven’t learned anything from ORNGE, eHealth or gas plants,” said interim Progressive Conservative Leader Jim Wilson, referring to previous Liberal government scandals about the provincial air ambulance service and electronic health records agency.

“You’re continuing your propensity as Liberals to just throw more money after bad … you owe the taxpayers an explanation,” he added in the first question period since the legislature rose for its summer recess in late July.

Wynne said those documents are commercially sensitive and releasing them now would cause problems — echoing the McGuinty administration’s line when opposition parties sought details about cancelled gas plants in Oakville and Mississauga before the 2011 election as compensation agreements were negotiated and costs snowballed.

“We’re not going to undermine an arrangement that would be in the best interest of the people of Ontario by providing information publicly that needs to be confidential for a period of time,” Wynne told the legislature.

“He should be careful,” she shot at Wilson, repeatedly refusing to say if there was a business case for the loan to MaRS, short for the Medical and Related Sciences biotech hub across from Queen’s Park.

That has opposition parties suspicious, with NDP Leader Andrea Horwath charging “it seems to me this government’s got a lot to hide.’

“Private investors would not put the money in (and) … must have seen something in that business plan or in those documents that we’re not seeing,” said Conservative MPP Randy Hillier.

Hillier said sensitive documents could be released to MPPs on the legislature’s estimates committee for an in-camera session.

Infrastructure Minister Brad Duguid said that is “a possibility” and that he has asked officials to sift through MaRS documents to release “whatever it is they can that’s not commercially sensitive. I think that’s fair.”

The 20-storey MaRS tower is located next to the original MaRS building on the southeast corner of College and University. It is just 30-per-cent occupied and having trouble finding tenants.

“It doesn’t look like there’s any opportunity for it to be rented and the taxpayer’s on the hook for at least $300 million, we just don’t know how much more,” said Hillier.