BEIJING, AP -Coal dust caught fire in a mine in northeast China, sparking an explosion that killed at least 68 people and left 79 missing, the government said Monday, as the country”s leadership called for tighter work safety measures.

Some 221 miners were underground when the blast occurred late Sunday at the Dongfeng Coal mine in Qitaihe, a city in Heilongjiang province, the official Xinhua News Agency said.

Seventy-four miners had been rescued by Monday, it said.

Xinhua said a 269-member rescue team was searching for the trapped miners and that Li Yizhong, minister of the State Administration of Work Safety, told them to &#34spare no efforts&#34 to save the workers.

China”s coal mines are the world”s deadliest. Fires, floods, cave-ins and explosions are reported almost daily, and thousands of miners are killed every year despite the government”s repeated attempts to improve its record amid lax safety rules and poor equipment.

Efforts to shut down dangerous mines have been complicated by the country”s soaring demands for power to drive its booming economy.

Chinese President Hu Jintao and Premier Wen Jiabao urged officials to curb the &#34possible occurrence of big safety accidents which claim huge casualties and property losses,&#34 the state-run newspaper China Daily said Monday.

The leaders called for enforcement of stricter inspections and punishments, it said.