Output from the field, which is shared with Iran, will rise from 77 million tonnes a year now.

Last year, Qatar Petroleum announced it was planning to develop additional gas from the North Field and build three new LNG mega trains.

"Based on the good results obtained through recent additional appraisal and testing, we have decided to add a fourth LNG mega train," said CEO Saad Sherida Al-Kaabi in a statement.

The new project will produce about 32 million tonnes per year of LNG, 4,000 tonnes a day of ethane, 260,000 barrels a day of condensate, and 11,000 tonnes a day of LPG, in addition to approximately 20 tonnes per day of pure helium, Qatar Petroleum said.

This will increase Qatar's total production capacity from 4.8 to 6.2 million barrels of oil equivalent per day, the statement added.