(Adds Suncor comments)

CALGARY, Alberta, Sept 30 (Reuters) - Canadian regulators approved the hydrotest results of Enbridge Inc’s Line 9 crude oil pipeline on Wednesday, clearing the way for the delayed 300,000 barrel-per-day route to the east of the country to start operating.

The newly reversed Line 9 will ship mainly light inland crude from Sarnia, Ontario, to Montreal, Quebec. It previously flowed in the opposite direction, taking imported crude to Ontario.

The line, originally expected to start up in late 2014, was held up after the National Energy Board ordered hydrostatic tests at three locations along the line in June.

Prior to that, regulators had asked for additional data on shut-off valve placements at major water crossings. {ID:nL1N0VG160]

The NEB said on Wednesday there were no further pre-operation requirements on Line 9.

“The successful hydrotests confirm the NEB’s confidence in the integrity of the pipeline and its confidence that the line can safely be returned to operation,” the regulator said in a statement.

The Line 9 approval is a rare bright spot for backers of Canadian pipeline projects, which include TransCanada Corp’s Keystone XL and Enbridge’s Northern Gateway.

These projects have run into fierce environmental opposition, and last week Democratic U.S. presidential candidate Hillary Clinton said she opposed Keystone XL.

The approval was welcomed by the Canadian Association of Petroleum Producers and Suncor Energy, which owns a refinery in Quebec and is one of Line 9’s biggest customers.

“We have long said the pipeline is critical in terms of improving access to inland crude and providing supply options to the Montreal refinery, which in turn enhances its competitiveness,” said Suncor spokeswoman Sneh Seetal.

Valero Energy Corp also has a refinery in Quebec and will likely benefit from being able to replace imported crude with cheaper inland barrels.

Once the pipeline becomes operational the NEB has imposed conditions including biweekly patrols, quarterly integrity testing and an in-line inspection within the first year of operation.

Enbridge is also required to limit the pressure of the pipeline for its first year of operation. It was not immediately clear whether pressure restrictions would affect the capacity of the pipeline and the company does not yet have an expected in-service date for the pipeline.

“There are still some technical preparations that are required and line-fill is not an exactly timed process, so we will not speculate at this time on a specific date for return to full service,” White said.