A strike at Fluxys' liquefied natural gas (LNG) terminal in Dunkirk, northern France, has been extended to Monday, a union official told Reuters.The strike, part of action against the government's plan to increase the state pension age, was most recently due to end on Friday.France's three other LNG terminals, operated by Engie subsidiary Elengy, are expected to be blocked until March 21.(Reuters - Reporting by Forrest Crellin; Editing by Mark Potter)