The move has surprised traders and triggered a sell-off in spot natural gas from Asia to Europe. More LNG could be sent to energy-starved Europe, helping to ease pressure from its abnormally low inventories and curtailed supplies from top exporter Russia.

China National Offshore Oil Corporation (CNOOC) is offering to sell one cargo per month between May and November, while Sinopec, is seeking to sell as many as 45 cargoes for delivery through October, according to traders with knowledge of the matter.

The tenders represent roughly four per cent of China's total LNG imports last year in one of the biggest offerings from the nation.

China spent much of last year buying spot LNG supplies and restocking inventories in preparation for this winter. But milder weather has left its energy giants with a glut of scheduled shipments. Reselling the cargoes into the pricey spot market could provide a profitable windfall for traders.