Canadian regulators are failing to monitor the country's nuclear power plants properly and such safety lapses are unacceptable, an official said Tuesday.

Canada has four nuclear plants with a total of 19 reactors in Ontario and New Brunswick provinces. They provide about 17 percent of the nation's electricity.

Regulators have carried out inadequate and irregular inspections, and these also failed to take into account risks when deciding which plants to probe, Commissioner of the Environment and Sustainable Development Julie Gelfand said.

"I think it's pretty serious," she told a press conference.

"This kind of lack of precision in a precision industry I think is really not acceptable," she said. "These mistakes should not happen when we're dealing with nuclear power plants."

The commissioner also said that some inspections scheduled between 2013 and 2015 were pushed back a year or more because technical specialists were not available, or because of an outage or a rescheduled reactor shutdown.

Furthermore, the Canadian Nuclear Safety Commission (CNSC) was often slow to release the results of its investigations, the watchdog lamented.

"We concluded that the CNSC could not show that it had adequately managed its site inspections of nuclear power plants," Gelfand said.

"The CNSC could not demonstrate that its inspection plans included the appropriate number and types of inspections and that it had the staff needed to verify that nuclear power plants were complying with all applicable requirements or that site inspections were carried out according to the CNSC's procedures," she added.

The CNSC responded that its oversight procedures are comprehensive but acknowledged the need for better documentation.

Prime Minister Justin Trudeau sought to reassure parliamentarians and the public, saying his government would "work to ensure that Canada has the highest standards on nuclear safety and security."