The death toll from a coal mine gas blast in north China has risen to 104 after rescuers found 34 bodies overnight, state television reported on Friday. The explosion hit the Xinyao mine in coal-rich Shanxi province late on Wednesday, but the managers did not report it until five hours later and instead tried to launch their own rescue operation, which Chinese media said probably increased casualties. Police were trying to confirm the exact number of people working underground, but it had "seriously exceeded safety limits" and rescuers were searching for more victims, China Central Television said. There were 15 survivors. The village-run mine was licensed, but initial investigations showed the explosion was caused by mining along a coal seam that had not been authorised for production, Chinese media said. Police have arrested the mine’s head and legal representative, suspended its licence and frozen its bank accounts, while top safety officials had rushed to the site from Beijing, Xinhua news agency said. China has been trying to tighten safety regulations but its coal industry is still the world’s deadliest, claiming close to 5,000 lives last year. China has warned coal mines to pay special attention to safety as they ramp up production to meet winter heating and power demand, the official Xinhua news agency said. In the week ending October 28, six colliery accidents left 41 miners dead or missing, the report said, citing a notice from the State Administration of Work safety. "Malpractice and illegal behavior must be stopped. All accidents must be handled immediately and strictly in line with laws," it quoted the notice as saying, adding the danger was greatest in the fourth quarter, the peak season for mining. Beijing has ordered provinces to close small, unlicensed mines, which are where most disasters happen, but rising coal prices on the back of an economic boom have meant some owners have ignored the order. "The battle to rectify coal production and to meet China’s rapidly surging coal demand will continue to be arduous for the world’s largest coal producer and consumer," Xinhua said.