Thousands of litres of synthetic drilling mud spilled at the White Rose oil development hundreds of kilometres southeast of St. John’s on Tuesday, officials say.

Husky Energy said the spill of about 5,000 litres of drilling mud from the GSF Grand Banks oil rig occurred during normal drilling operations.

The White Rose oil project is about 350 kilometres from the island of Newfoundland. Drilling was suspended Tuesday and an investigation was launched, the Canada-Newfoundland Offshore Petroleum Board said.

Drilling mud is used in the oil industry to prevent oil or gas from escaping during drilling operations.

The news release suggested the spill is not expected to have a serious impact on the environment near the rig.

"Synthetic based mud is a heavy, dense fluid used during drilling operations to lubricate the drill pipe and balance reservoir pressure. Because of its weight, the mud sinks rapidly in the water column and rests on the sea floor. The synthetic base oil used is a food-grade oil of extremely low toxicity," said a C-NLOPB news release Tuesday.

Late last March, more than 26,000 litres of drilling mud spilled from another oil rig operating east of St. John's. The Henry Goodrich rig was drilling an exploration well for Suncor at the time.

According to the C-NLOPB, the incident in March was the largest spill of drilling mud since 2007, when 74,000 litres of drilling mud were spilled in the Orphan Basin area of the North Atlantic Ocean.

With files from The Canadian Press