BEIJING -- A plastic bag ban launched five years ago has cut consumption by at least 67 billion bags, saving an equivalent of 6 million tons of oil, the National Development and Reform Commission (NDRC) said Friday.

Since the ban was implemented, use of plastic bags has dropped by more than two-thirds, said Li Jing, vice chief of energy-saving and environmental protection department under the NDRC, China's top economic planner.

China banned the practice of offering free plastic bags in supermarkets, department stores and grocery stores, as well as prohibited the production and use of plastic bags thinner than 0.025 mm starting from June 1, 2008.

However, some vendors still offer free bags, as well as bags that are too thin.

The government will tighten supervision and better enforce the ban in the future, Li said.