Canadian energy company Nexen said safety was its top priority after a provincial regulator ordered dozens of pipeline closed because of maintenance issues.

The Alberta Energy Regulator issued a suspension order to Nexen Energy, a Canadian subsidiary of the China National Offshore Oil Corp., calling on the company to shut down more than 90 of its oil and gas networks after the company was found to be in non-compliance with federal regulations.

The order came after last month's report of a failure on the company's Long Lake pipeline network in the province. About 31,000 barrels of a mixture of oil, water and sand spilled in Alberta from the system.

"Given that this company has already had a pipeline failure at this site, the AER will not lift this suspension until Nexen can demonstrate that they can be operated safely and within all regulatory requirements, " Jim Ellis, the regulator's top official, said in a statement. "We will accept no less than concrete evidence."

Nexen in a statement said it started an internal audit of its pipeline networks in July, which it said identified "a number" of non-compliance issues.

"Nexen considers regulatory compliance to be of the utmost importance in our operations, and we are committed to continuous improvement, regulatory compliance and cooperation with the AER," it said in a statement. "Our top priority is the safety of our employees, the public and the environment."

Environmental group Greenpeace applauded the AER decision. Oil sands found in Alberta are a heavier grade of crude oil that can sink in water and linger in the environment longer than other types, making cleanup operations complex.

Greenpeace said Nexen in particular has a poor environmental track record, estimating the company was tied to at least 130 spills in the Alberta in roughly the last decade.

"This [suspension] decision should send a message to all pipeline operators that lax safety procedures that put Alberta's environment and communities at risk are not acceptable," campaigner Mike Hudema said in a statement.