But some experts believe it is sending a dangerous signal - that protecting the environment is not really important.

Coal mining contributes to global warming

The "dash for gas", now temporarily halted, played a significant part in helping to reduce UK emissions of the main gas involved in global warming, carbon dioxide (CO2).

However, a greater use of coal could stop that trend, environmentalists believe.

Under the terms of the agreement reached at the meeting of governments in the Japanese city of Kyoto last year, the world is committed to cutting its emissions of all greenhouse gases to five per cent below their 1990 levels, and to reaching this target some time between 2008 and 2012.

UK's ambitious targets

The countries of the European Union are responsible for achieving eight per cent of this target, with the UK share of the EU cuts more ambitious still - a commitment to achieve a reduction amounting to 12% of the savings the entire EU has to make.

On top of that the government has promised to cut our emissions of CO2, the gas given off by burning fossil fuels, by 20% before the 2010.

The UK has an impressive record in emissions reduction

The UK's record on combating climate change by cutting its output of greenhouse gases is already one of the best in the world. But two factors made that possible - the "dash for gas", which meant a switch away from coal, and the reduction in heavy industry that came with the recession of the early 1990s.

Friends of the Earth has mixed feelings about the government's announcement. A spokeswoman said the group supported a moratorium on the building of new large gas-fired power plants, in order to protect the diversity of fuel supplies and prevent the country becoming too dependent on any one source.

And she said allowing coal a bigger role would give more scope for CO2 cuts in the next century. She said that, according to FoE's own modelling work, there was a place for coal in the UK's energy policy. But she said the coal that was used should come from deep pits, not from opencast sites or as imports from abroad.

London city skyline in smog

One energy analyst, though, described the government's announcement as "an irrelevant political gesture, a figleaf allowing it to appear to be doing something for the mining communities who have borne the brunt of the greenhouse cuts".

Andrew Warren, the director of the Association for the Conservation of Energy, said the government was sending the wrong signal with its announcement.