Environmental NGOs have taken advantage of China's revised Environmental Protection Law to file lawsuits, but public interest litigation in 2015 lagged behind expectations, a key organization reported.

More than 1,000 organizations were qualified to file lawsuits, based on changes in the law, yet only nine started filings, said Ge Feng, head of law and policy department of Friends of Nature.

Organizations also have confronted many thorny problems in filing lawsuits against environment pollution and damage, as the revised law still does not address some issues, she said.

Xie Yuhong, deputy secretary-general of the All-China Environment Federation, an nongovernmental organization supervised by the Ministry of Environmental Protection, said public interest litigation involving the environment saw smoother growth last year than in 2013 and 2014.

The revised law became effective on Jan 1, 2015. Together with other supplementary regulations, the environmental NGOs have seen a lower threshold for lawsuits, "which made last year the best time in the past decade for the federation," Xie said.

The nine organizations filed 37 lawsuits nationwide. Nearly half targeted water pollution, while 14 percent targeted air and water pollution jointly, and others involved soil pollution, ecological damage and other issues, according to the survey conducted by the federation and Ge's Beijing-based Friends of Nature.