Intact Financial Corp (IFC.TO), Canada's largest property and casualty insurer, said second-quarter earnings per share fell by 54 per cent due to the impact of the wildfires in the Alberta oil city of Fort McMurray.

The company said on Wednesday earnings per share fell to 67 cents from $1.47 the year before. It said the average estimate of analysts who follow the company was 55 cents.

Net operating income fell by 46 per cent to $114 million, or 83 Canadian cents per share. Excluding the impact of the Fort McMurray catastrophe it would have risen by 15 per cent compared with the same period the previous year.

"This is a strong testament to the resilience of our operations across the country," said Chief Executive Officer Charles Brindamour. "Our catastrophe response is well underway in Fort McMurray and we remain committed to helping our customers get back on track."

The wildfires are expected to cost insurers $3.6 billion in total, making it the costliest-ever Canadian natural disaster, an insurance industry group said this month.