TORONTO - The Ontario government investigated 26 deaths involving its troubled air ambulance service over the past six years, secret government documents show.

The deaths were related to 145 incidents involving Ornge since 2007 that were investigated by the Ministry of Health, according to the confidential papers obtained by the Progressive Conservatives.

They included delays in dispatching air ambulances, paramedics unable to perform CPR due to cramped conditions in the helicopters, staff shortages and paramedics running out of supplies like oxygen and medication.

Chief coroner Andrew McCallum said Friday that his office has investigated all of the Ornge cases brought to its attention, and some investigations are still ongoing.

"Of our completed investigations, there have been no cases in which issues with air ambulance transportation materially affected the course of the patient's illness or injury," McCallum said.

One investigation of a car crash in the London area on July 17, 2011, noted that Ornge didn't respond to the call -- even though there was an aircraft available in Toronto -- because its dispatch centre was waiting to see "if the patient was hurt enough." One person died and the coroner was notified.

Forty of the incidents -- five of which involved the death of a patient -- were opened this year, after the government installed new leadership at Ornge.

They include a May 17 incident in Toronto where there was a delay because the stretcher jammed. The patient died.

In February, there were two incidents in February where Ornge was unable to respond to a request for an air ambulance because there were no pilots on duty and others in February and March where Ornge didn't have paramedics on duty.

During another transport in March, paramedics ran out of portable oxygen, which raised the patient's heart rate.

"The physician stated the paramedics told her they had made complaints to Ornge in the past regarding a lack of oxygen supplies on aircraft and nothing has been done," it notes.

The documents included details about some recent high-profile cases, including a four-hour delay in transporting a 69-year-old woman from Barry's Bay to Ottawa, about 150 kilometres away. She died two days later.

Not all 145 incidents reflected poorly on Ornge. In some cases, the ministry concluded that Ornge was not at fault or there wasn't enough evidence to substantiate complaints.

The documents, dated May 23 and drafted by the ministry's emergency health services branch, are marked "Confidential -- For Cabinet Purposes." But Matthews said they were not provided to cabinet and the last update she'd seen was May 10.

She noted that only 16 of the 40 incidents actually occurred in 2012. The others happened in past years but weren't reported until this year.

Both Matthews and Premier Dalton McGuinty expressed confidence Friday in Ornge's new leadership, who were appointed by the government.

"They are working very, very hard to ensure that they have appropriate staffing levels," Matthews said in an interview.

"It's not something that they turn around immediately. There is hard work that they are doing."

Yet the minister has insisted for months that she's taken decisive steps to fix Ornge, Conservative Frank Klees said Friday.

"We are so frustrated in this legislature that the same minister continues to stand in her place and pronounce that she has taken decisive action, when people continue to die, when we continue to have response calls that can't be accommodated," he said.

But Ornge said it's made "significant progress" over the past few months to improve patient safety.

"We take every incident seriously," spokesman James MacDonald said in a statement.

The government is ultimately responsible for the deaths of those patients because it failed to keep an eye on Ornge, Klees charged.

"The reason I say that is because at the end of the day, there were people in charge who had oversight responsibilities who allowed this to continue," he said.

Ornge knew in late 2010 that there was a problem with its faulty helicopter interiors, but nothing was done until a year later when it became front-page news, he said.

"Anyone with any sense of responsibility would have taken immediate steps to ensure that that issue's addressed," Klees said.

"If that is not being responsible for whether it is a death, or whether it is simply being responsible for the appropriate and proper care not being administered, I don't know what is."

The documents have added fuel to the firestorm that's engulfed Ornge -- and the governing Liberals -- for months.

Ornge, which is under a criminal probe for financial irregularities, has been under fire for questionable business deals, high executive salaries and allegations that public money may have been used for personal gain.

Auditor general Jim McCarter slammed the government in March for failing to oversee Ornge, despite giving it $730 million over five years and allowing it to borrow another $300 million.

A legislative committee heard earlier this week that several incidents where patients died were related the design of the interiors of Ornge's AW-139 helicopters.

They included jammed stretchers, critical patients unable to sit upright and paramedics unable to perform CPR.

Ornge paid $144 million for 12 helicopters from Italian firm AgustaWestland, whose dealings with Ornge have come under intense scrutiny. Ornge also paid $6 million for the Swiss-manufactured Aerolite medical interiors.

It even sent a team to Switzerland to oversee the design.

Tom Lepine, who was fired as Ornge's chief operating officer, said he only discovered the problem with the medical interiors in late 2010, after the first chopper went into service.

Ornge is still looking for a permanent fix for the interiors. It said a temporary fix has been made to all the helicopters that addresses some of the most serious concerns.

McGuinty wouldn't say Friday whether he would testify before the committee, saying the police should do their work first and that the public should rely on the auditor's report.

Asked if that was a "no," McGuinty responded: "That's an interesting response to your question."