A natural gas platform in the Gulf of Thailand has attracted a fresh warning over methane emissions first detected more than a decade ago, another test of global pledges to curb releases of the potent greenhouse gas.

Emissions from the site, operated by a joint venture between units of two state-backed energy companies — Malaysia’s Petroliam Nasional Bhd. and Thailand’s PTT Exploration and Production Pcl — have been observed at least 60 times by satellite since 2013, and the owners were most recently urged in May to address the problem.