Banning flimsy plastic bags has been dismissed as a drop in the ocean when it comes to dealing with the world's environment problems, but multiplied on a China scale, it appears to have made a big difference.

A new report suggests restrictions on bag usage in the world's most populous nation have saved the equivalent of 1.6 million tonnes of oil, in the year since it was introduced.

Just ahead of the first anniversary of the ban, the China Chain Store and Franchise Association estimated it had saved the country 40 billion plastic bags.

According to their survey, plastic bag use has fallen by two thirds as consumers grow accustomed to bringing their own reusable bags.

The ban was introduced on 1 June 2008 to reduce "white pollution" – the popular term for plastic bags and styrofoam packaging. Under the new rules, the state forbade production of ultra-thin bags under 0.025mm thick and ordered supermarkets to stop giving away free carriers.

That surprise move – which went further than anything done by the US, the UK and many other developed nations – was hailed by Greenpeace, Earthwatch and other green groups as a sign of growing environmental awareness in China. It also lead to the closure of the state's biggest plastic bag manufacturer.

Although the ban is often flouted, particularly at street stalls and small shops, it is widely praised for helping to change attitudes.

"It has made an impression," said recent graduate Xuyang Jingjing. "I see more people carrying 'green bags' to supermarkets these days. But I think if the government really wants people to stop using plastic bags, it should have the shops giving out green bags for free."

But there is a long way to go. China produces a million tonnes of rubbish a day with the volume looks set to rise.