The Liberal Democrats want to see the end of petrol-powered cars by 2040 as part of radical proposals to tackle climate change.

Their environment spokesman, Chris Huhne, said that under his party's proposals, cars would be powered by hydrogen fuel cells, improved batteries or as-yet undeveloped technology.

Mr Huhne said there had been "far more dramatic changes" in Britain's economic history.

He said such a change compared with the shift from the steam engine to the internal combustion engine or from the gas light to the electric light at the start of the 20th century.

If the EU worked together through the internal market, the plans could become reality, he said.