Enbridge Inc (ENB.TO) (ENB.N), North America's largest pipeline operator, on Thursday reported a lower-than-expected profit, hurt by outages and production disruptions at its liquids pipeline business.

The company said it expects the performance of its liquids pipelines business to strengthen over the rest of the year as production and throughput ramps back up on its mainline system.

Quarterly profit more than tripled, helped partly by the company's US$28 billion purchase of natural gas pipeline company Spectra Energy Corp.

Earnings attributable to shareholders rose to C$919 million , or 56 Canadian cents per share, in the second quarter ended June 30, from C$301 million, or 33 Canadian cents per share, a year earlier.

Excluding one-time items, the company earned 41 Canadian cents per share.

Analysts on average had expected earnings of 48 Canadian cents per share, according to Thomson Reuters I/B/E/S.