A state news agency says the death toll in a northeast China coal mine blast has jumped to 87.

The official News Agency says another 21 people are still trapped underground after the pre-dawn blast at the state-run Xinxing mine in Heilongjiang province near the border with Russia.

The massive explosion cut power in the mine as well as ventilation and communication links, hampering the efforts of more than 300 rescue workers.

A total of 528 people were working in the mine at the time of the 2:30 a.m. explosion and 389 escaped after the blast, the latest to hit China's mining industry, the world's deadliest.

The mine is located near the border with Russia, about 250 miles (400 kilometers) northeast of the provincial capital, Harbin.

It is run by one of China's top 520 state-owned enterprises, according to the Web site of its owner, the Hegang branch of the Heilongjiang Longmei Holding Mining Group. It says the Hegang branch has more than 88,000 employees.

China depends heavily on coal to generate about three-quarters of its electricity needs.

The government has been cracking down on unregulated mining operations, which account for almost 80 percent of the country's 16,000 mines.

The closure of about 1,000 dangerous small mines last year helped to cut in half the average number of miners killed, to about six a day, in the first six months of this year, the government has said.

Major gas explosions in coal mines remain a problem, though the number of accidents and deaths have gradually declined year by year, the chief of the State Administration of Work Safety, Luo Lin, told a national conference in September.

In the first nine months of this year, China's coal mines had 11 major accidents with 303 deaths, with gas explosions the leading cause, according to the central government.

Most accidents are blamed on failures to follow safety rules, including a lack of required ventilation or fire control equipment.

A blast at the Tunlan coal mine in northern China's Shanxi province killed 77 people in February in China's worst industrial accident in a year.