London Councils, the body that represents the capital's authorities, has moved to initiate legislation to ban free disposable plastic bags in the city.

The initiative came in response to a poll of 1,700 people that showed 90% wanted either an outright ban or a levy of 10 to 15p per bag.

London newsagent Haresh said some lateral thinking would be required about what to give customers.

"Maybe I'll give them the cardboard boxes stock arrives in," he said. "That would be green - and cheaper." Plastic bags cost him 1p each, but paper bags are 2p and the initiative could add to the costs of his business.

However, shopkeepers such as Haresh probably have plenty of time to make plans.

The 33 council leaders from around London who met today cannot banish plastic bags themselves, and the proposed legislation, contained within the ; London local authorities bill, will only begin to be debated in parliament on November 27.

After the meeting, the London Councils chairman, Merrick Cockell, said: "The campaign to rid the capital of the environmental blight of throwaway shopping bags begins here.

"As a society, we need to do far more to reduce the amount of landfill, and London as a city is determined to take an ambitious lead on this issue. I urge all Londoners to voice their support to their MP and back the bill once it gets to parliament."

Today's move came a week after Brighton & Hove council offered support for a voluntary ban. It is the largest authority to have done so, while around 80 smaller towns are also considering a voluntary ban.

The London Councils call for a ban instead of a levy could reflect a lack of central government enthusiasm for the kind of plastic bag tax introduced in Ireland with questionable success.

The Department for the Environment's website says: "There is no clear evidence that such a tax would be beneficial on either broad environmental or litter grounds.

"This is because people would be encouraged to use bags made from other materials or alternative means of packaging, which may be equally or more damaging to the environment."

Cities such as San Francisco and Dacca in Bangladesh have, however, succeeded in reducing the use of plastic bags through taxation.

The British Retail Consortium (BRC) said the London bag tax idea was "born of ignorance" because the voluntary agreement with retailers to reduce the environmental impact of plastic bags by 25% by the end of 2008 was proving sufficient.

Yesterday, Sainsbury's revealed it had seen the use of its free carrier bags drop by 10% – equal to 85m disposal bags and 750 tonnes of landfill - in the past six months compared with last year. It said the use of reusable bags had risen by 50%.

The BRC director, Keith Hawkins, said plastic bags would always be needed for "unplanned shopping trips" and for retailers to pack expensive items such as clothes or electricals to "beat the rising tide of shoplifters".