TORONTO - The Progressive Conservatives are questioning why Ontario's chief coroner hasn't yet called an inquest into more than two dozen patient deaths involving Ornge, the province's troubled air ambulance service.

Details surrounding the deaths were contained in confidential documents intended for cabinet that were released by the Tories last Friday.

The Health Ministry investigated the deaths while probing 145 incidents involving Ornge since 2007.

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.

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.

In a statement released late Friday, chief coroner Andrew McCallum said there were no completed cases "in which issues with air ambulance transportation materially affected the course of the patient's illness or injury."

But it's odd that McCallum hasn't called an inquest, given the number of deaths and the circumstances surrounding some of the cases, Tory Frank Klees said Monday.

One patient died after a car crash in the London area in 2011. Ornge didn't respond to the call -- even though there was an aircraft available -- because its dispatch centre was waiting to see "if the patient was hurt enough," the confidential documents said.

Another case that was sent along to the coroner involved the transport of a patient in Sudbury, where the paramedic said he couldn't perform CPR because of the cramped conditions inside the Ornge helicopter. The paramedic accompanied the patient in a land ambulance, but the patient died.

The ministry's investigation found that continuous CPR couldn't be performed due to the interiors of Ornge's new AW-139 helicopters and that patients in respiratory distress couldn't be provided with appropriate care.

Klees said McCallum's statement raises more questions than it answers.

It appears to be very carefully worded and didn't say there was conclusive evidence that Ornge's failure in transporting patients didn't contribute to their deaths, Klees said.

"It's very clear that the coroner was asked to provide this document so it could be used by the government to defend itself today," he said Monday.

Dr. Dan Cass, deputy chief coroner for investigations, said that's not true and the coroner merely wanted to clarify his involvement in the Ornge cases.

"We were not asked to put anything out," he said in an interview.

The ministry's emergency health services branch sent 10 Ornge-related reports to the coroner, Cass said. A number of them had triggered a coroner's investigation under the law and had been probed already.

Six of the 10 investigations have been completed and four are ongoing, he said.

"To the best of our knowledge, in the ones that we have concluded our investigation, we didn't identify any of them where the air ambulance transport has any impact on the course of the illness or injury," Cass said.

It's premature to say whether an inquest will be called, he said.

"That's not to say that we wouldn't be open to considering any number of actions," Cass added.

"A coroner's inquest is one way that we fulfil our public safety mandate. The chief coroner himself can make recommendations on any case where there's a coroner's investigation."

Premier Dalton McGuinty and Matthews both used McCallum's statement as a shield while under opposition fire in the legislature Monday.

"I think it's important to take a look at what the coroner has to offer in this regard," McGuinty told the legislature as he read McCallum's statement.

But that wasn't enough for the Opposition, who demanded that he fire Matthews.

"Now we see, despite all the questions in the house and the media, the minister not even sharing this document of the detailed wreckage happening at Ornge today," said Tory Leader Tim Hudak.

"If this is not it, premier, where do you set the bar? It is time for this minister to resign."

Ornge, which is under a criminal probe, has been rocked for months by allegations about questionable business deals, high executive salaries and whether public money was used for personal gain.

Ontario's auditor general has criticized the government for failing to oversee Ornge, despite giving it $730 million over five years and allowing it to borrow another $300 million.

A legislative committee is also holding hearings on Ornge and has called in many former executives and bureaucrats to testify.