By Ben Blanchard

BEIJING (Reuters) - A top Chinese Communist Party official on Tuesday called on private bosses to keep their workers on the payroll as he warned of the impact of "complex and severe" economic conditions on China's stability.

An estimated 20 million migrant workers have lost their jobs as demand for Chinese exports has dried up, creating the risk that their discontent could translate into protests or other threats to Party rule.

The economy, and maintaining social stability, are at the top of the agenda of China's annual parliament meeting which begins this week.

"We encourage people from the non-public sector ... to shoulder their share of social responsibilities and work hard to ensure that no employees in their enterprises are laid off, or suffer pay cuts, or wage arrears, in order to create harmonious labor relations," Jia Qinglin told the Chinese People's Political Consultative Conference, an advisory body that meets once a year.

Provincial and central government officials have urged state owned enterprises to reduce salaries in order to keep workers employed and limited state-owned firms' abilities to fire large groups of workers.