The Warehouse will charge 10c for plastic shopping bags from next month in an effort to encourage the use of reusable bags.

The company says it wants to take 20 million bags out of circulation in the next year, after a survey revealed that 78 per cent of its customers would support a change to reusable bags.

The Warehouse chief executive Ian Morrice said trials throughout the country showed that customers often did not need a plastic bag, as a large majority of purchases were only two or three items.

"We found eight out of 10 customers didn't need a plastic bag, so they avoided buying one. So for most people it is going to reduce their consumption.

"Not everyone is happy with it initially ... but the mass majority of customers avoided the plastic bags altogether.

"Overseas research, coupled with this trial recently ... suggests that applying a small charge to checkout bags directly results in reduction."

A survey of 600 customers in the four trial stores - at Alexandra, Rotorua, Hawera and Pukekohe - revealed that 85 per cent of consumers would not use plastic bags if they had to pay for them.

Customers can also buy reusable bags for 99c.

Mr Morris said the initiative was not a profit-making exercise, and that the 10c charge would be reinvested in community projects local to the stores. "For those customers who have been sceptical from the outset, that has been a reassuring factor. We're not looking to make money out of this exercise." He said the company did not intend to eliminate plastic bags altogether.

The Warehouse's plan was part of a larger movement, under the Packaging Accord 2004, to reduce plastic bag use in New Zealand by a fifth by July this year.

So far, 100 million bags have been taken out of circulation, most (86 million) in the past two years as the campaign has gained momentum.

Foodstuffs, Progressive Enterprises, Woolworths and The Warehouse were among those to sign the Packaging Accord. Retailers such as Mitre 10 and Caltex have also joined the campaign. Others, including Bunnings and Borders, have their own bag reduction scheme.

The Warehouse will begin charging for plastic bags on April 20.