Brunei LNG's plant, which was shut down unexpectedly on June 12, is likely to resume production on June 13, a source with knowledge of the matter told Reuters.

"Safe restart of the plant is in progress and production is expected to resume later on Tuesday," the source said, adding that the shutdown was due to "an unforeseen external event."

Brunei LNG did not immediately respond to a request for comment.

Its plant, which has a capacity of 7.2 million tonnes per year of LNG, was shut down on June 12 as the company investigated black smoke and flaring at the site, Brunei LNG said in a statement on June 12.

It did not say how long the plant would be shut for, or the reason why, stressing that the focus was on restoring plant operations safely.

Brunei LNG is 50% owned by the government of Brunei, and the rest is split equally between Japan's Mitsubishi Corp. and Shell.