Qatargas will stop three of the world\'s biggest liquefied natural gas (LNG) producing plants at different times during a rolling maintenance programme planned for this autumn, the world\'s largest LNG producer said on Sunday. European gas prices leapt on Friday after traders with knowledge of the situation revealed that Qatargas trains 5, 6 and 7 would shut consecutively for around two weeks each from mid September to early November — when heating demand from big buyers in Europe and north-east Asia climbs as temperatures fall. Qatargas did not give exact dates or durations for the closures of the plants. The company operates seven LNG trains with a capacity of 42 million tonnes per annum (mtpa), but has signed several deals since March to sell more LNG to new markets in addition to Japan.