MELBOURNE, March 28 (Reuters) - Oil Search Ltd OSH.AX launched a legal fight on Friday contesting French oil giant Total SA's TOTF.PA purchase of a 40 percent stake in Papua New Guinea's biggest undeveloped gas field.

Oil Search recently bought a 23 percent stake in the Elk and Antelope fields, controlled by another PNG company, InterOil Corp IOC.N , which this week signed a final agreement selling down its stake to Total. ID:nL4N0MN1N9

Oil Search said on Friday it had filed a notice of dispute to InterOil regarding Total's acquisition. The company's investor relations head was not immediately available to comment on the grounds for the dispute.

After buying into the fields, Oil Search had expected to have pre-emptive rights over the stake being sold to Total. The PNG oil and gas producer is hoping to hold sway over how the fields are developed.

Oil Search wants the Elk-Antelope gas to supply an expansion of the $19 billion PNG LNG project, led by ExxonMobil Corp

XOM.N , while InterOil and Total want to build a competing standalone LNG project.

Oil Search is a 29 percent stakeholder in the PNG LNG project, which is due to start exporting around July.

(Reporting by Sonali Paul; Editing by Stephen Coates)

((Sonali.Paul@thomsonreuters.com)(+61 3 9286 1419)(Reuters Messaging: sonali.paul.thomsonreuters.com@reuters.net))

Keywords: PAPUA OILSEARCH/TOTAL