Up to 20,000 miners rioted in a north-eastern Chinese town after their mine was closed, prompting the authorities to send in troops to restore order.

The protest in Yangjiazhangzi was sparked by anger at low redundancy payments in an area with little alternative employment prospects.

It happened in February, but was not covered by state media, and has only now come to light.

Further unrest has been reported in the south-western province of Sichuan by coal miners blocking railway tracks in protest at impending lay-offs.

Troops fired into air

Officials confirmed that in the Yangjiazhangzi protest, 20,000 miners and their families had taken to the streets.

They were protesting at the level of redundancy payments on offer.

Reports say they blocked streets, smashed windows and damaged vehicles after police tried to intervene.

Several hundred troops from nearby towns were called in.

According to the Hong Kong-based Information Centre for Human Rights and Democratic Movement in China, they fired their guns into the air to restore order.

There are no details of arrests or injuries, but local officials said the government was holding a dialogue with the miners in an attempt to reach a settlement.

The mine, which produced molybdenum for the electronics and aerospace industries, was the area's only major employer.

At least five million workers are due to lose their jobs nationwide this year as China continues radical reforms of its state enterprises.

BBC Beijing correspondent Duncan Hewitt says the mining industry is particularly vulnerable to the drastic economic reforms.

In the coal-mining sector alone, more than 20,000 mines are due to close.

Rail disruption

In the latest protest by miners in Sichuan province, 500 workers blocked rail traffic on on the Guiyang-Kunming railway for several hours on Saturday.

According to reports from Hong Kong, the miners from the Liuzhi mine were protesting after the enterprise went bankrupt, threatening the jobs of 40,000 people.

Local authorities are reported to have sent in several hundred police to clear the tracks.

At least 10 similar protests have erupted on the railway line in recent months, according to the Information Centre for Human Rights and Democratic Movement in China.

It says the biggest occurred in December when some 10,000 stopped rail traffic for half a day.