Didcot power station is one of the worst places in the country for pumping out greenhouse gas carbon dioxide, according to new figures.

Didcot A power station, above, produced 6.3m tonnes of carbon emissions last year - more than 50 per cent over its allowance under the European Emissions Trading Scheme aimed at trying to reduce greenhouse gases.

The company will now have to buy additional permits from companies that did not use their allowance to cover the shortfall.

RWE nPower said the figures for the coal-fired Didcot A station were inevitable and it had never expected to hit the emissions targets set by the UK Government.

But the company added it fully supported the European Trading Scheme aimed at cutting C02 emissions.

RWE nPower spokesman Leon Flexman said: "Coal power stations pre-date concerns about C02 and the country still relies on them for much of its power. The key thing is how to replace them.

"We're already the biggest operator and developer of wind farms in the UK, we have cleaner gas power stations, including Didcot B, and are looking at building more.

"We're also researching building new 'clean coal' power stations where the CO2 is captured and stored."

But Mr Flexman said the transition to cleaner fuels could not happen overnight.

He added: "In the meantime we have improved the efficiency of Didcot A to make it as clean as possible and we're also burning 'carbon neutral' organic fuels.

"Didcot A will very likely close in the next decade, but for now it is very much needed, unless people rapidly start to use much less energy in their homes and businesses."

But Didcot district councillor Sara Davidson was angered by the new figures.

She said: "What's the point of government telling people they should switch to low energy light bulbs in order to slow down climate change and then let industry get away with carbon pollution on this scale?

"Didcot Power station is putting this town on the map for the wrong reasons. We need local firms to be good corporate citizens not world class polluters."

Drax Power Station in North Yorkshire was the most polluting site in 2005, producing 20.8m tonnes of carbon dioxide, 6.2m tonnes above its allowance.