At the National Commodity and Derivatives Exchange, refined soya oil for delivery in January month rose Rs 5.90, or 0.92 per cent to Rs 644.65 per 10 kg with an open interest of 57,415 lots.
Similarly, the oil for delivery in February contract gained Rs 5.20, or 0.81 per cent to Rs 647.25 per 10 kg in 70,640 lots.
Analysts said speculators built up fresh positions on the back of strong demand in the spot market against restricted arrivals from producing belts.