In mid-July, Canadian Natural Resources Ltd. published a 92-page report on the 2013 seep of more than 12,000 barrels of bitumen, the viscous form of oil found in Alberta.
Canadian newspaper the Toronto Star reported Tuesday it obtained more than 100 pages of emails showing the enforcement branch of Environment Canada called on a spokesman to "limit information" released about the spill last year.
The Star reports the seeps began in May 2013, but weren't disclosed until July when the newspaper issued its accounts of the incidents.
Megan Leslie, a provincial lawmaker from Halifax, told the newspaper the government of Prime Minister Stephen Harper was massaging public relations about the energy sector.
"The responses (to media) don't need to be beefed up," she said. "Our environmental enforcement needs to be beefed up. The investigation process needs to be beefed up."
The Canadian company said initially that legacy issues at the site may have led to the incident, but noted in its report a process dubbed cyclical steam stimulation, or CSS, may have contributed to what the report described as a flow-to-surface event.
CSS may have cracked open other subsurface layers, allowing oil to leak out of control from the site.