SIOUX FALLS, S.D. -- Oil is flowing once again through the Keystone pipeline after a leak in South Dakota caused a shutdown that lasted more than a week.

TransCanada says in a news release that the cross-border line was restarted Sunday following permission that was granted by the Pipeline and Hazardous Materials Administration in the U.S.

The company says the line will operate at a reduced pressure as part of the plan that was approved to return it to service.

The leak, which was reported April 2, let over 63,000 litres of oil seep into a South Dakota field in Hutchinson County.

The company has said on-site specialists and regulators have not observed any significant environmental impact.

It says cleanup and land restoration has already started and will continue over the coming days.

"Our goal over the 40,000 miles of pipeline we have operated for the past 65 years is zero incidents. We will apply what we learn from this incident to move us closer to that goal," the company said.

The pipeline runs from Alberta to refineries in Illinois and Cushing, Okla. It's part of a pipeline system that also would have included the proposed Keystone XL pipeline, which was rejected by President Barack Obama last November.

The company says it continues to conduct aerial patrols and visual inspections of the site.