More workers are suffering occupational diseases than ever before, and 80 percent of them have pneumoconiosis, or known as black lung disease, the country's top legislature said.

Huang Zhendong, director of the Internal and Judicial Affairs Committee of the National People's Congress (NPC) Standing Committee, said the accumulated number of people with a workplace-related disease was about 700,000 in 2008. The number of sufferers was 670,000 in 2006.

"The rate of occupational disease has been on the rise since 2005," Huang said in an address to the bimonthly session of the 11th NPC Standing Committee.

"Workers face many troubles in receiving compensation when they find they have contracted an occupational disease."

He said the number of new occupational disease cases stood at 11,159 and 14,296 in 2006 and 2007 respectively.

Most of the occupational diseases were reported in small and medium-sized firms and about 80 percent of the diseases were black lung diseases, of which coal miners are typically sufferers, Huang told legislators.

"There have also been more labor disputes and mass incidents resulting from the damage of occupational disease," he said.

Huang's report was based on the findings of an NPC investigation in how the Trade Union Law was being implemented in Liaoning, Jiangsu, Hunan, Guangdong and Sichuan provinces, as well as Shanghai.

The report follows the case of Zhang Haichao, a 28-year-old migrant factory worker, who spent two years trying to prove that he suffered from dust lung disease.

Shi Fumao, a lawyer with the Beijing Legal Aid Office for Migrant Workers, one of the few organizations that offer free legal advice to migrant workers, said Zhang's case demonstrated how hard it is for workers to get compensation for occupational diseases.

"It is much harder than asking for salary entitlements," said the lawyer who has also dealt with numerous cases of bosses refusing to payout employees' wages.

Workers often faced difficulty in getting diseases diagnosed, he said. Huang also said that since the beginning of the global financial crisis there had been an increase in cases where employers disappeared without paying wages to employees.

A total of 1,985 such cases were reported during 2008, affecting more than 206,000 employees owed a total of more than 600 million yuan, he said. By the end of last year, 212 million workers had joined the trade union, including 66 million migrant workers, Huang said.