It said the gas supplies had been halted from the Chaivo field to the Okha - Komsomolsk-on-Amur pipeline on Feb. 1 at 0145 local time.

"We've had an unplanned stoppage of gas flows from the field to the pipeline. The consumers continue taking off gas from the stockpiles, accumulated in the pipeline," a spokesman for Exxon Neftegaz Ltd, the operator of the project, told Reuters.

Sakhalin-1, on Russia's Sakhalin island in the Pacific Ocean, operates under a production sharing agreement struck in the mid-1990s. ExxonMobil has 30 percent of the project, Russia's Rosneft and India's ONGC have 20 percent each, while Japan's SODECO consortium owns 30 percent.