The plastic bag’s status as a symbol of waste was confirmed yesterday as Gordon Brown pledged to help to eliminate its use in Britain.

He threw his weight behind the growing campaign against disposable carriers in his first big speech on the environment since becoming Prime Minister. Speaking before an international climate change summit in Bali next month, Mr Brown confirmed that the Government’s target of a 60 per cent reduction in Britain’s greenhouse gas emissions by 2050 may be extended to 80 per cent.

Environmentalists also welcomed his statement that Britain was committed to meeting its share of an EU target to generate 20 per cent of Europe’s power from renewable sources by 2020. John Hutton, the Business Secretary, is expected to announce plans soon for a significant expansion in offshore wind farms. Insisting that fighting climate change would not hamper economic growth, he said that Britain’s leadership of a new green technological revolution could create hundreds of thousands of new jobs.

In a speech to the WWF conservation group in London, Mr Brown said that transforming the world’s energy economy would require a “fourth technological revolution”. It would, he said, change society as fundamentally as had steam power, the internal combustion engine and the microprocessor. “This represents an immense challenge for Britain but it is an even bigger opportunity,” he said. “Building our own low-carbon economy offers us the chance to create thousands of new British businesses, hundreds of thousands of new British jobs and a vast new export market in which Britain can be a world leader.”

The Climate Change Bill currently going through Parliament will commit Britain to 60 per cent cuts in greenhouse gases by 2050, with interim targets in a “carbon budget” every five years. Mr Brown said, however, that the latest evidence suggested that developed countries may have to reduce their emissions by 80 per cent over that timescale.

Mr Brown said that the plastic bag had become one of the most visible symbols of environmental waste. They have been banned in scores of towns and villages in recent months and London local authorities have become the latest to discourage shops from handing them out.

Supermarkets have already promised to reduce by 25 per cent the environmental impact of the bags they give out but, announcing new talks with retailers, Mr Brown said that he believed it was possible to phase the carriers out completely. Officials said later that ministers were to press the EU for cuts in the VAT rate imposed on greener alternatives.

“It is a relief that the Prime Minister has reconfirmed our commitment to the EU 20 per cent target,” Philip Wolfe, the chief executive of the Renewable Energy Association, said. “However, after ten years of talk a huge gap has opened up between the political rhetoric on climate change and the reality of wholly inadequate policy and financial support.”

Tony Juniper, the director of Friends of the Earth, added: “If green speeches by our political leaders were enough, climate change would have been solved many years ago. We genuinely hope that, at long last, the Government will show real urgency and put combating global warming at the heart of all its policies.”

Peter Ainsworth, the Shadow Environment Secretary, said: “Gordon Brown’s record on the environment so far has consisted of missing targets, then scrapping them, then cutting the budgets that deal with them.”

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