BEIJING -- A spokesman for China's work safety regulator said on Friday that coal mining remains a high-risk industry in the country despite improvements over the past decade.

Speaking at a press conference in Beijing, Huang Yi, of the State Administration of Work Safety, said that 35 workers are currently killed in coal mines for every 100 million tons of coal output in the country, about 10 times the death rate in the United States.

Small coal mines, accounting for about 85 percent of the nation's 12,000 mines, are the biggest source of danger due to poor safety provisions. They cause two thirds of the all deaths annually in the sector, even though their output makes up only one third of the nation's total, said Huang.

The spokesman said the nation aims to close another 625 small coal mines this year in an attempt to reduce the number of deadly accidents.

In recent years, authorities have been pressing ahead in these efforts by setting timetables for mines to improve safety measures, while ordering them to invest more to beef up facilities. New rules released in April require that dangerous mining enterprises funnel at least 30 yuan ($4.7) for each ton of production back into improving safety.

"We must stay clear-headed all the time and be on alert for coal mine safety," according to Huang.

Government data showed that 1,973 miners were killed in coal mine accidents in 2011, 19 percent fewer than in 2010.