Ontario's opposition parties demanded answers Friday about high salaries at the province's air ambulance system and accused the Liberal government of stonewalling their attempts to get the information.

After years of opposition demands for more information and media attempts to find out salaries at the air ambulance service, the Toronto Star reported Friday that ORNGE air ambulance chief executive Chris Mazza is paid $1.4 million a year.

Mazza went on an indefinite medical leave Thursday, just hours before his salary -- the highest for anyone paid by Ontario taxpayers -- was made public.

"We've got a guy now on medical leave from a salary of $1.4 million per year, and we've got issues with how ORNGE has been operated as an ambulance service," said Progressive Conservative Peter Shurman.

"The McGuinty government has been aware of this for a couple of years, so we're not talking about something new."

The Tories have been demanding answers about salaries and operations at ORNGE for years, said Shurman, only to have the government rebuff their inquiries.

"We're delighted that the auditor general has heeded our calls for an investigation," he said.

"And we're delighted that a government that has stonewalled the questions in the legislature is finally going to have to do something about an agency that is vital to the health and safety of Ontarians."

The New Democrats also demanded the Liberal government answer for what they called "the outrageous secrecy and salaries" at ORNGE.

"After months of stonewalling and cover-up this government has run out of excuses," said NDP health critic France Gelinas.

"They need to start providing some real answers now."

The opposition parties want Health Minister Deb Matthews to release all salary details and other documents from ORNGE, saying the agency had earlier submitted the information to the government.

On Thursday, Matthews announced she was looking into executive salaries at ORNGE after receiving what she called "troubling and concerning information," and said the provincial auditor general would look into the agency.

"The government knew there was a big expensive mess at ORNGE," said Gelinas.

"How can the Minister be 'shocked' by salaries she already knew about?"

The government sent a team of forensic auditors to review the financial documents at ORNGE "to ensure taxpayers get the transparency and accountability they deserve," said Matthews.

Once the review is completed, the government will "take any action required" to ensure value for taxpayers, she added.

ORNGE said in a statement that it welcomed the minister's decision and has fully complied with her requests.