BEIJING -- Top legislator Zhang Dejiang on Sunday pledged to enhance environmental legislation and oversight of pollutant emissions, giving hope that the country's long-debated environmental protection law can be revised this year after several unsuccessful attempts to do so.

As smog continued to shroud Beijing, Zhang, chairman of the National People's Congress (NPC) Standing Committee, said the top legislature's 2014 to-do list includes revisions to the environmental protection law and the air pollution prevention and control law.

By improving laws and regulations, China will tighten oversight of pollutant discharges, and inflict harsher punishments for illegal practices, Zhang said, stressing that polluters responsible for environmental damage must be held to account.

His words came just days after Premier Li Keqiang "declared war" against pollution on Wednesday, pledging to fight it with the same determination with which the country battled poverty.

Revising the environmental protection law, which took effect in 1989, has been deemed central to curbing pollution. However, the past three attempts to amend the law have been unsuccessful, with unsatisfied lawmakers calling for stricter measures and more government obligations.

It is quite rare in China for a law or amendment not to be passed after three readings. Another such case involved the property law, which was finally passed in March 2007 after eight readings.

Fighting pollution has long been on top of the government's agenda, but a spell of smog that enveloped some 15 percent of the country's territory a week ahead of the annual parliamentary session added urgency to the matter. Beijing at one point recorded "beyond-index" measurements of particulate matter.

Zhang said prominent environmental problems, such as air, water and soil pollution, are of great public concern and stressed that protecting the environment is an urgent and complex task that requires long-term efforts.

The NPC Standing Committee will carry out investigations on preventing and controlling soil pollution, and seek to solve prominent environmental problems and strengthen ecological conservation, he said.

Zhang's comments were echoed by Ouyang Song, a member of the NPC Standing Committee and former director of the Party history research center of the Communist Party of China Central Committee.

"We should improve the incorporation of environment impact assessment in approving future projects and invite the public to join environmental assessments to enhance oversight," Ouyang said.

Meanwhile, authorities should also specify the subjects, scope and conditions of accountability in the sphere of environmental protection, so as to further control pollution, he urged.