TORONTO - Ontario's troubled air ambulance service faced at least 13 disruptions over the last three weeks that may have jeopardized patient safety, the Opposition charged Wednesday.

Ornge helicopters in London and Sudbury were grounded for days because there were no pilots, said Progressive Conservative Frank Klees, who is demanding the health minister's resignation.

"I have a list of 13 other incidents over the last few weeks," he told the legislature.

"They deal with incidents such as this: a helicopter sent to the wrong hospital in London resulting in a lost bed for a pediatric patient due to a three-hour delay on the part of Ornge ... (a) London helicopter sent to Simcoe helipad that had no lights because the dispatch department didn't know it," Klees said.

All the incidents were reported by whistleblowers who are fed up with the situation at the troubled agency, he said.

"There are dispatches being made that are, quite frankly, dangerous," Klees said outside the legislature.

"And there are circumstances happening every day that are concerning pilots and paramedics, and I'm told that it is all about patient safety and crew safety at this point in time."

Ornge and Health Minister Deb Matthews couldn't immediately confirm nor deny the incidents. But Matthews promised that every incident on Klees's list will be investigated.

She noted that Ornge has a new interim CEO and board of directors who are cleaning up the agency and shutting down its controversial for-profit ventures.

"I have every confidence that the new board is very, very focused on patient safety," Matthews said.

The new board is looking at allegations that safety requirements weren't being met at Ornge and making changes "on patient safety issues," she said.

Ron McKerlie, Ornge's interim president and CEO, said late Wednesday that he took any allegations of incidents "very seriously."

"Ornge has in place an investigation process and we encourage anyone with concerns about a specific transport to contact us directly," he said in an emailed statement.

"While I acknowledge there are challenges, patients can rest assured they are getting high quality care when they are being transported by Ornge crews."

McKerlie added that he had been reviewing operations since his arrival in January and said there were a "number of issues" he was dealing with which could not all be fixed immediately.

But, he said he had initiated several improvements at the service.

Ornge also said it had experienced "some challenges" staffing helicopters because of of pilots being unavailable. Two pilots are needed for a helicopter to fly, if no replacement can be found for those unable to fill their shifts, the aircraft is out of service.

The opposition's latest charges about Orgne aren't the first complaints involving patient safety at the service. The agency is currently looking for a permanent fix for the interiors of its AW139 helicopters -- the design made it difficult for paramedics to perform certain life-saving procedures, such as CPR, on patients.

Ornge said a temporary fix has been made to all helicopters that addresses some of the "most serious clinical concerns."

The Ministry of Health's emergency health services branch is also investigating 13 incidents related to air ambulance transports, three of which involved deaths of patients.

Ornge, which receives about $150 million a year from the province, is currently under a criminal probe for "financial irregularities."

It's been under a cloud of controversy for months over exorbitant executive salaries and questionable business practices, including whether its maze of for-profit subsidiaries were funded with public dollars.

Matthews said the province is doing everything it can to recoup any money that was lost. But it's too early to tell if taxpayers will be on the hook to cover any debts incurred by the for-profit companies, she said.

Both opposition parties are calling for Matthews' resignation over the scandal, saying she failed to properly oversee Ornge and didn't act on complaints about the agency until it became front-page news. But the minister said she's not going anywhere.

Matthews must step aside if the government is serious about restoring public confidence in Ornge, said NDP Leader Andrea Horwath.

"Let's face it: this minister has known for a long time that this organization has had questionable practices, not only financially but otherwise," she said.

"And here we are, years later, finally getting to the bottom of some of it."