KHOBAR, Saudi Arabia, May 13 (Reuters) - Saudi Basic Industries Corp (SABIC) expects its planned oil-to-chemicals plant to start operations by the end of 2020, it said on Tuesday. SABIC, one of the world's largest petrochemical groups, said it expects to use around 10 million tonnes of crude oil annually as feedstock for the plant. That is equivalent to 200,000 barrels per day, or an average-sized oil refinery. In its first public an**uncement on the project, SABIC did **t say where the complex would be located, how much it would pay for the oil or if the crude would be subsidised.