An oil leak at the site of the Hibernia offshore platform on the Grand Banks off the coast of Newfoundland has resulted in a significant downturn in oil production.

Workers reported a small leak on Dec. 18. Hibernia management company officials said it happened in a valve that is part of the rig's offloading system. Only 10 litres of crude oil spilled at the time, and no oil sheens were spotted on the water at that time.

However, on Dec. 27, oil was discovered in the ocean once again, and a further investigation revealed the valve was leaking. The small sheen was rapidly dispersed by heavy seas, and by Jan. 3, it was no longer visible.

As a result of what was observed, Hibernia has shut down the transfer of oil to tankers, and the company says it has "significantly" cut back oil production.

Crews have been arranged to fix the leaking valve as soon as the weather permits.