(Bloomberg) -- China’s coal prices may extend gains after rising to the highest in more than 15 months as inventories at Qinhuangdao port fall to the lowest in at least six years. Larger-than-expected cuts in domestic production have tightened supplies and prices will likely continue to climb during peak-power demand in the summer, according to David Fang, a vice director at China Coal Transport and Distribution Association. Output fell 9.7 percent to 1.63 billion metric tons in the first half of the year amid broader efforts to curtail industrial overcapacity.To contact Bloomberg News staff for this story: Jing Yang in Shanghai at jyang251@bloomberg.net. To contact the editors responsible for this story: Ramsey Al-Rikabi at ralrikabi@bloomberg.net, Alpana Sarma .With assistance from Jing Yang