By Holly Williams BBC, Beijing

Two leaders of a labour protest have been released from prison in China after spending nine months locked up without charge.

The men led around 30,000 laid-off workers in several weeks of protests against the government and the managers of their factory in Liaoyang City in the country's north east.

Two other leaders of the March demonstrations, Yao Fuxin and Xiao Yunliang, remain in custody.

Large-scale demonstrations are still unusual in China but the country's crumbling state-owned enterprises and increasing unemployment could spark increased unrest.

Wide-scale corruption

Pang Qingxiang and Wang Zhaoming are out of prison, but they are far from free.

This is a probationary release and they have been told that they are not to meet with other laid-off workers but instead to gather evidence against their fellow protesters.

Most of the protesters in Liaoyang worked for the city's Ferro-Alloy Factory, a bankrupt, state-owned enterprise.

The Liaoyang protest was the largest demonstration in China for years

When the factory closed, employees were promised pensions and back wages.

But they never materialised and many of the unemployed workers suspected the factory's managers of massive embezzlement.

They took to the streets in China's largest public demonstration in years.

The police eventually cracked down but across China state-owned companies are faltering, weighed down by bad business practices and corrupt managers.

In Chinese cities, that has raised the unemployment rate to dangerous levels - perhaps as high as 15%.

The government now has Liaoyang under control, but in future it may have many more protests to deal with.