Petroleum minister Dharmendra Pradhan today said, state-run ONGC, OIL and BPCL will in the next four years invest USD 6 billion in developing a giant gas field off the Mozambique coast. Mr Pradhan, who returned from a two-day visit to the African nation last night, said the first LNG from the block is targeted for 2018-end or early 2019. The project with capacity to produce 20 million tonnes of LNG annually would be the world's largest LNG export site after Exxon Mobil-run Ras Laffan in Qatar.