Fatih Birol, Executive Director of the International Energy Agency attends the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 17, 2017. The global oil market is expected to rebalance in the second half of 2017, but further output increases among key producers such as Nigeria and Libya could hamper this process, International Energy Agency chief Fatih Birol said on Tuesday. He said some key producers including Libya and Nigeria had significantly increased output in recent months. “In the current context we see the market rebalancing in the second half of the year. But if production increases in some of the key producers this may change the picture,” Birol told Reuters on the sidelines of an Energy Institute event. “Whatever OPEC do, if the prices go up, there will be a response from shale oil producers,” he said. (Reporting by Ron Bousso; Editing by Hugh Lawson)