Fourteen migrant workers who contracted black lung disease due to inadequate safety measures at work have been compensated by the social security fund in South China's Shenzhen city.

The migrants, who are among dozens demanding compensation, have been paid a total of more than 2 million yuan (US$294,000), a spokesman with the Shenzhen Trade Union said on Wednesday.

While the official refused to reveal the exact amount paid to each migrant, Zhong Jiaquan, one of the victims, said it ranged from 20,000 to 280,000 yuan each, depending on the severity of the case.

Four other migrants, including Zhong, are still waiting to receive compensation because they are not covered by Shenzhen's social security program.

Their employers had refused to compensate them, Zhong said.

The outspoken and eloquent Zhong has been at the forefront of the fight for the migrants' rights since 100 of them showed symptoms of lung disease in September last year.

The workers, all from central Hunan province, claimed inadequate safety measures were in place at highly-polluted workplaces. Their jobs involved drilling and blasting at more than 10 businesses in Shenzhen.

Eighteen were diagnosed with black lung disease in January by the Shenzhen prevention and treatment center for occupational diseases.

The center has yet to verify the test results from the No. 2 People's Hospital in Shenzhen, which found in January that 41 other migrants were suffering from the same disease, the trade union spokesman said.

The union and the local labor and social security authority are negotiating with their employers over the compensation dispute. Zhong said his employer, Haofengda Engineering Co, had refused to compensate him.

His condition was diagnosed as "medium-stage pneumoconiosis", for which he can expect to receive up to 200,000 yuan in compensation.

Black lung, or pneumoconiosis, is a chronic occupational disease caused by prolonged exposure to mine dust. There is no specific treatment for the ailment, according to the Chinese Medical Association.