Canadian Ontario provincial government warned residents of the incident at the Pickering nuclear power plant, later admitted to sending the wrong notice.

The announcement was sent to the phone of people in Ontario, central Canada at 7:22 pm today, saying "there was an incident at the Pickering nuclear power plant, but there was no radioactive material leaking into the environment."

Authorities later admitted the message was mistakenly sent. "Important update: There is no danger to the public and the environment," the Twitter account of the Ontario Energy Administration, which operates the Pickering plant, posted the status line. The cause of the confusion has not been announced.

Pickering mayor Dave Ryan said he was reassured that no emergency had occurred, but said he was worried about receiving such a false notification. "I have been in dialogue with the provincial government and am requesting a full investigation," Ryan added.

Toronto Mayor John Tory also complained that three million city residents had been meaninglessly alerted and called for an investigation because "there are too many unsolved questions".

The Pickering plant, which has been in operation since 1971, is one of the world's largest nuclear power facilities with eight reactors and a maximum capacity of 3,100 megawatts.