Green campaigners have urged Environment Minister Edwin Poots not to waste any time but to take the plunge and introduce a tax on plastic bags.

And they have warned that to be effective in deterring people from using plastic bags the charge needs to be set at up to 25p a bag.

The minister said he would consider introducing a levy if the present system fails.

A 15 cent levy introduced in the Republic in 2002 has resulted in a dramatic 90% reduction in the number of plastic bags being used. The minister said he would initially consider a similar levy in Northern Ireland at the end of July.

Northern Ireland’s ‘bag lady’, Shirley Lewis, who is funded by the DOE to persuade people to cut plastic bag use, said she was dubious about figures quoted by supermarkets: “When I go shopping with one of my dozens of reusable non-plastic bags, I see a lot of brand new bags coming out of the shop doors,” she said.

“Why is it taking so long to do something so simple?”

She said Mr Poots should set a deadline for deciding whether existing arrangements work.

“I think people are often subconsciously waiting for somebody else to take responsibility – we need to take responsibility now, not wait for three-four years,” she said. “It’s time to move forward on this – I think once it’s happened, people will really respond. At heart we are quite mean with our pennies and people will want |to economise.”

Ian Humphreys, chief executive of Tidy Northern Ireland, estimated that Northern Ireland people use around 150 bags per person per year and urged the minister to take action now.

“We would prefer if it was a mandatory levy on plastic bags. We are about changing behaviour and that is an effective way of changing behaviour,” he said,

“Plastic bags are seen as something that is free but we pay for it — we just don’t see the cost attached to it. It’s madness letting this go on when we see what happened in the Republic.”