The supermarket chains, owned by two of Hong Kong's biggest trading companies, are seeking to block moves to impose a 50 HK cents plastic bag levy on their customers.

The 50-cent-a-bag pilot trial was proposed by the Green Student Council, a non-governmental organisation, and supported by the Environmental Protection Department in a bid to reduce Hong Kong's plastic bag consumption.

Green groups say bags are no longer supplied free with purchases in places such as Taiwan, Shanghai and Ireland, dramatically cutting their use by consumers.

In Ireland, they say, bag use was reduced by 90 per cent after a levy of about HK$1.40 per bag was introduced.

In Taiwan, plastic bag use fell by 80 per cent after a levy of 30 HK cents was introduced in 2002.

Plastic bag use is a growing concern because, according to the Council of Sustainable Development, Hong Kong's existing landfills will be full in 11 years.

But the supermarkets said on Friday they have no intention of amending their current system of a 10 HK cents cash rebate for every plastic bag not used, claiming they are being unfairly targeted.

The Green Student Council said its members will stage a protest today and submit a 5,000 signature petition supporting the levy to supermarket supremos Li Ka-shing, whose Hutchinson Whampoa conglomerate controls ParknShop, and Ronald Floto of the Jardine Matheson-controlled Dairy Farm, which operates Wellcome.

They said they will also surround the supermarket companies' headquarters at Cheung Kong Centre, Central, and Taikoo Place with chains made from plastic bags.

The council wants an environmental fund set up should a green tax be imposed, so that income from the levy goes directly into environmental use instead of the government's treasury.

Financial Secretary Henry Tang proposed a green tax on plastic bags and tyres to legislators earlier this month.

``This is a very good time for us to rethink the bag levy issue,'' said Angus Ho of the Green Student Council. ``The tax will take a long time to implement but we need to do something in the meantime.''

A spokeswoman for Wellcome said the government has not contacted the chain to follow up the trial programme proposal since representatives from the government, green groups and supermarkets met in August.

She said that if a levy is introduced it should apply to all retailers and not just the two supermarket chains.

``We're willing to co-operate in environmental protection, but it's unfair to target us as all supermarkets together were responsible for only 8.6 per cent of the total plastic bags used in 2003,'' she said.

``About HK$600,000 has been spent on the cash rebate system each year since the company introduced it in 1997, and 33 million bags have been saved in that time.''

But Ho said the 8.6 per cent figure was misleading and that the supermarkets remain the largest users of plastic bags and bear responsibility under the polluter-pays principle.

Wellcome and ParknShop together operate about 500 stores in Hong Kong.

A ParknShop spokeswoman said the 10 HK cents rebate is already well above both the net and landfill costs of each bag, which is about five cents.

In rejecting the 50-cent levy, the chain said it will have a ``negative business impact'' on its operations.

ParknShop has ``already made progress'' in reducing bag use, with 2.2 million bags saved from January to July this year, according to the spokeswoman.

But Ho estimates that fewer than 40 bags are saved from each ParknShop and Wellcome branch each day.

A recent Green Student Council survey revealed that one-third of the 10 million bags given out by supermarkets each day are unnecessary.

sylvia.hui@globalchina.com