(Updates with details and Chevron comment from paragraph 3)

SYDNEY, Sept 17 (Reuters) - Australia's Offshore Alliance union said on Sunday that workers had begun a second 24-hour strike at Chevron's liquefied natural gas (LNG) plants in Western Australia.

"Another 24hr stoppage has been applied across all 3 facilities with 15% of Downstream members enacting rolling stoppages/bans after midday today," an Offshore Alliance representative, who declined to be named, said.

The strike would run until 8 a.m. on Monday (0000 GMT), the union representative said, adding that meetings would be held "twice a day everyday" to decide on further strikes.

Chevron said it would not comment on the strikes and that its focus was maintaining safe and reliable operations in the event of disruption.

Workers on Saturday ramped up their industrial campaign against the U.S. energy major with an initial 24-hour strike that ended at 8 a.m. (0000 GMT) on Sunday.

Offshore Alliance on Saturday said it intended to extend industrial action for a further two weeks to mid-October.

Prior to this weekend there have been more limited work stoppages at the remote LNG facilities after pay and condition talks between the union alliance and Chevron broke down this month.

Chevron has asked Australia's industrial tribunal to intervene in the dispute and cancel the strikes. The tribunal is set to hold a hearing on the matter on Friday.

Chevron's Australian LNG facilities account for over 5% of global supply, but analysts say the strikes will likely be temporary and pose little risk to the market, while key gas buyers already have enough inventory ahead of the northern hemisphere winter. (Reporting by Sam McKeith in Sydney; Editing by William Mallard and Tom Hogue)