By the BBC's Jake Lynch

A new tax, presented by the government as part of its green agenda, is being criticised for threatening one of Britain's most important recycling industries.

The Aggregates Levy, which came into force this year, penalises firms for extracting materials like sandstone from quarries, with a charge of �1.60 per tonne.

It could raise hundreds of millions of pounds a year, and it has led the industry to begin using glass from bottle banks, grinding it down into sharp sand to use in road building.

But the glass industry says it should have a prior claim on discarded glass, to recycle into bottles and jars.

Recycling glass

Andy Hartley, of Rockware Glass in Knottingley, West Yorkshire, explained that the higher the proportion of recycled glass in their furnaces, the less energy they use in making glass containers.

"For every 10% of recycled glass we use, we make an energy saving of 3%, and energy is our biggest cost," he said.

He says recycling glass in this way therefore delivers a much greater environmental gain than using it to make sand.

Mr Hartley is "very concerned" about the Aggregates Levy because over the last two years since it became clear that it would be introduced, the aggregate industry has claimed an increasing share of glass.

Britain has a surplus of green bottles

This comes at a time when his business could easily double its consumption, he claims.

The aggregates industry itself says Britain actually has a large surplus of green glass because it imports so much wine. It believes there is far more green glass available than the UK packaging industry can use.

One company now producing road building materials from glass is Day Aggregates, of Charlton, in South East London.

Contracts Manager Miles Willingale said they had recycled 17,000 tonnes of glass in the last year, working with local authorities to take the contents of London bottle banks and use it to produce sharp sand, which the councils can then use in roads and pavements.

"They have really warmed to the idea", he said.

Government plans

The government plans to use money raised from the Aggregates Levy for a Sustainability Fund to develop recycled sources of building materials.

A spokesman for the Department for Environment, Food and Rural Affairs said that in terms of alternatives to quarrying, the rule was "the more the better".

But everyone concedes that the energy locked up in a manufactured product, like glass, is far greater than in a raw material like sand.

Britain will have to step up recycling in the next few years to meet tough European targets, and in time there may be plenty of glass to go round.

For the moment, the glass industry says the Aggregates Levy is imposing an order of priorities which is counter-productive to its green intentions.