TORONTO -- Teachers' unions weren't asked to provide any receipts or invoices before the Liberal government handed them $2.5 million for extra bargaining costs -- and no such documentation was needed, the education minister insisted Thursday.

This year's talks with teachers and support staff unions were the first under the Liberals' new two-tier bargaining system, and the unions incurred extra costs because it was an especially long process. When the government decided to help cover those extra costs, there was "some discussion" about the amounts, but no full accounting, Liz Sandals said.

"You're asking me if I have receipts and invoices; no, I don't," she said.

"We know how long we've been at the hotel. We know what hotel rooms cost. We know what the meeting rooms cost. We know what the food costs. We know what 100 pizzas costs. You don't need to see every bill when you're doing an estimate of costs."

If the estimates turn out to be incorrect, Sandals was asked, will she ask the unions to return the difference?

"No," she said. "But I actually don't think I'm paying the full cost. They have costs far in excess of what we are supporting."

The government agreed to pay the Ontario Secondary School Teachers Federation and the Ontario English Catholic Teachers' Association $1 million each, as well as $500,000 to the French teachers' union, to compensate them for an extra-long process under the Liberal government's new bargaining system.

The government also compensated the school boards and trustee associations involved in central bargaining, Sandals said, though she wouldn't disclose the amounts.

"I make no apologies for supporting everybody who is involved in the transition," she said.

The circumstances will not recur because in the next round of bargaining, the parties won't have to start from scratch, hammering out each and every clause, Sandals said.

It's not the first time the government has given the unions some compensation. As other central models were explored in 2004, 2008 and 2012, there were "supports," Sandals said. Again, she refused to say how much.

"To be perfectly obvious, I didn't spend it. I wasn't the minister," she said. Premier Kathleen Wynne was education minister from September 2006 to January 2010.

"I'm not sure that it is useful to go back and rake through the history."

In the previous round of bargaining, the Liberal government imposed a wage freeze, angering the teachers, who are challenging the legislation in court. Wynne eventually reopened the contracts, which the auditor general said cost Ontario taxpayers $468 million.

Progressive Conservative Leader Patrick Brown, who asked Wynne during question period where that money came from -- she didn't answer -- said it's a "complete disrespect for taxpayers."

"There has to be accounting," he said. "There has to be transparency. The fact the government can throw around a million dollars like it means nothing is, in my opinion, insensitive to the fact that we have huge needs in Ontario and the government spends money frivolously."

The three unions would not answer followup questions Thursday.

In the last provincial election, OSSTF, OECTA and the Elementary Teachers' Federation of Ontario put $250,000 each toward third-party advertising from the Working Families coalition, a group of unions that comes together each election to run anti-Tory ads.

Sandals shrugged off the optics of giving money, receipt-free, to unions that arguably helped the Liberals win a majority.

"During the 2014 election, when I was working in (my riding of) Guelph, the teachers' unions weren't supporting me, so I don't know why you're assuming that there is some sort of connection here between being opposed to the Tories and supporting me," she said. "That just doesn't actually factually exist."

ETFO, which has not yet reached a central contract with the government, announced Thursday that its members will be withdrawing from all voluntary extracurricular activities as of Wednesday to put pressure on Crown negotiators to return to the table.

Wynne and Sandals will meet Friday with ETFO and the unions representing support workers to discuss the ongoing negotiations and the impact of job action. The government has proposed new bargaining dates to ETFO and is waiting to hear back, Sandals said.