An oil spill into a major Canadian river from a Husky Energy Inc pipeline started on the evening of July 20, and crews did not arrive onsite until the following morning, the company said on July 26. Husky's incident report, released by the Saskatchewan government, said the leak into the North Saskatchewan River was discovered on June 20 at 8 p.m. local time in the western province.

Crews arrived at the site of the Saskatchewan Gathering System pipeline on the morning of July 21, Husky executive Al Pate told reporters on a conference call, but he did not say why crews went out the next day and not earlier.

Pate confirmed earlier statements from the company that it shut down the pipeline on the morning of July 21, and said Husky remains confident that its estimate of the volume of oil that leaked, 250 cubic meters, has not changed.

"The only thing I am aware of is that Wednesday night there were some irregularities in our monitoring system," Pate said. "The first indication we had a leak was early Thursday morning."

Pate, who said he had not seen the incident report, struggled to answer why it took Husky until the next day to respond to the irregularities and said there would be an investigation into the leak.

About 1,572 barrels of oil leaked into the North Saskatchewan River, forcing two western Canadian cities to stop drawing drinking water from the river.

The 19-year-old pipeline transports heavy oil and helps supply Husky's Lloydminster upgrader.

The market impact of the shutdown was likely to be limited because crude can be trucked to a number of other pipeline receipt points on the system, oil market players said.

Husky has declined to comment on whether there had been any impact on production.

In Canada's oil capital, Calgary, some analysts said that although the spill was relatively minor, it would fuel fierce opposition to new Canadian pipelines projects such as TransCanada Corp.'s Energy East and Kinder Morgan Inc.'s Trans Mountain expansion.

"It's another incident that anti-pipeline types and environmentalists... will latch on to to say this stuff is dangerous," said Martin King, an analyst at FirstEnergy Capital.