Demand for 10p plastic bag levy instead of a total ban

The aim is to reduce the number of disposable bags being issued, about 1.6 billion a year in London, as well as the amount of non-recyclable waste sent to landfill sites.

An investigation by the London Assembly said the levy - which it wants to apply to plastic and paper bags - would be more practical than the ban being sought by the capital's borough councils. Darren Johnson, Green chairman of the Assembly's environment committee, said plastic bags had become a "potent symbol of needless waste".

He said: "We have all come to recognise the way we package our food and other goods should change. The most obvious point at which to start is where our shopping finishes - the checkout. Handing out and accepting free shopping bags has become an unnecessary reflex."

The report comes a month after London Councils deposited a Bill in Parliament seeking to ban shops from providing plastic bags to Londoners.

This would prohibit all "shopping bags" except those used to wrap unpackaged food, pre-sealed packaging and bags for carrying items on planes, trains, buses and ships.

The restrictions would be enforced by council officials, who would be able to search premises if they believed the rules were being flouted. Breaches of the ban would be punished by fines of up to £1,000.

The Assembly report was based on experience in Ireland, which introduced a levy (currently 15p per bag) in 2002 that resulted in a 94 per cent reduction in their use, from 1.3 billion to less than 100 million.

Murad Qureshi, the committee's deputy chairman, said: "A national levy makes a lot of sense ... There is no reason why it won't work well here in the UK."

However, the report's publication was delayed after infighting at City Hall, with the One London party, which speaks up for small business, saying the success of a voluntary code set up by supermarket chains rendered a levy unnecessary. One London leader Damian Hockney said: "There is no need for any more government interference by putting an extra levy on the bags."

It also questioned claims that it takes 400 years for a plastic bag to degrade, and noted the knock-on effect in Ireland of a 77 per cent increase in plastic bin liners.

The Assembly said it would support stronger voluntary arrangements to reduce the issuing of bags if its call for a levy failed. It regards a London-wide ban as the third-best option. Should the ban be accepted by MPs, it will apply everywhere except Hounslow after the borough failed to pass a resolution in time to participate in the pan-London restrictions.