Statistics Canada says the energy sector was down 2.1 per cent in May -- its first decline in five months and its largest since August 2020.
Canada's record-breaking wildfire season led many mining and oil and gas companies to reduce their operations in Alberta.
The agency says modest growth in the economy in May was driven partly by a rebound in the public administration sector as most federal public servants on strike returned to work by the end of April.
However, StatCan's preliminary estimate for June suggests the economy contracted by 0.2 per cent.