Beijing - China will toughen its environmental protection laws to target polluters, according to a high-level policy report released on Sunday, paving the way for possibly unlimited penalties for polluting and the suspension or shutdown of polluters.

The revised law would hold "polluters accountable for the damage they cause and having them compensate for it", said the report, delivered by Zhang Dejiang, who sits on the seven-member Politburo Standing Committee as one of the country's most powerful politicians.

Premier Li Keqiang declared a "war on pollution" in a report during the country's annual parliamentary session on Wednesday, but critics say the statement amounts to mere rhetoric without legal reforms to back it up.

The environment has emerged as one of Beijing's key priorities amid growing public disquiet about urban smog, dwindling and polluted water supplies and the widespread industrial contamination of farmland.

Sources with ties to the leadership told Reuters in February that amendments to China's 1989 environmental law would expand the environment ministry's powers significantly and allow regulators to suspend and shut down repeat offenders.

Sunday's policy report did not give specific details on how enforcement would be toughened. China's environment ministry has historically been unable to enforce anti-pollution laws effectively.

Almost all Chinese cities monitored for pollution last year failed to meet state standards.

China tested a domestically-produced drone aircraft that disperses smog by releasing a chemical catalyst, state media reported on Sunday.