JAPAN:What would Japan do without its convenience stores? Dispensers of food, booze and hundreds of other products and services, including 24-hour ATMs to 35 million shoppers a day, the ubiquitous konbini is an indispensable part of Japanese life. Walk 50 metres in any direction in most cities and there's that neon sign glowing. That, say critics, is the problem.

Those lights, refrigerators and air conditioners running all day at 41,000 shops up and down the country gobble up power. Add to that the thousands of trucks and vans clogging up the roads to keep them stocked and you have a CO2-spewing monster, says environmentalist Yurika Ayukawa, vice chairwoman of an umbrella group of Japanese NGOs.

"We think they should close at night. It would be an important symbol of our commitment to cutting greenhouse gases."

Some local governments agree. Saitama Prefecture, north of Tokyo, plans next year to demand that store owners shut off their neon signs after 11pm and other cities may follow suit, including Tokyo. The demands are likely to grow; Japan is the world's fourth-largest polluter and emissions are running higher than they were in 1990, putting the government in breach of the Kyoto Protocol.

Last year, several Japanese cities baked in temperatures of nearly 41 degrees, breaking national records and sparking much soul-searching about global warming. Prime minister Yasuo Fukuda recently announced a plan to slash Japan's CO2 emissions by up to 80 per cent, a commitment that will inevitably affect the country's giant retail sector.

However, the local government plans have run into opposition. Junji Ueda, president of the FamilyMart chain, warned about a "witch hunt", prompting the government's top spokesman, Nobutaka Machimura, to wade into the debate.

"We just want convenience store operators to think it is an idea to consider, instead of feeling they are becoming some kind of scapegoat," he said.

Japan's former capital Kyoto was the first to feel this backlash recently when it asked convenience-store owners to "voluntarily refrain" from late-night openings. Although the request had no legal teeth, the press was quick to note that environment minister Ichiro Kamoshita gave it his blessing. "Leave our oases alone!" screamed one weekly magazine.