The Liberal Democrats have insisted green taxes will hit the rich rather than the poor.

The party's environment spokesman, Chris Huhne, used an article in a new book to say that his plans for increases in air travel and vehicle excise duties will fall on those on higher incomes the most.

Huhne's intervention is the latest contribution to a debate sparked by the chancellor's doubling of air passenger duty in his pre-Budget report last year.

The move sparked a furious reaction among airlines, with Ryanair chief executive telling this month's Parliamentary Monitor that Gordon Brown's increase in the levy had nothing to do with the environment.

"Gordon Brown has lied," Michael O'Leary said. "It's just a bloody tax grab."

He said the tax would hit "ordinary working families who take their one holiday a year on a fundamentally green and efficient airline like Ryanair".

But Huhne said Lib Dem proposals for higher environmental taxes were designed to ensure that wealthy households pay most.

He pointed to Civil Aviation Authority figures showing that just 20 per cent of leisure flights are taken by the poorest half of the population.

"The sharp fall in prices is one of the principal reasons for the explosive growth in flights," he said.

"Growth has been fuelled more by the frequent short breaks of the prosperous middle classes than by the foreign holidays of the less well-off."

On road transport he said the Lib Dems would tax gas-guzzling luxury cars rather than petrol in order to make the charge more progressive and provide an incentive to switch to greener vehicles.

Their plans would see Vehicle Excise Duty (VED) scrapped for hybrid engine cars altogether but raised to £2,000 for the worst polluting vehicles.

Huhne said a increasing VED rates was "much more likely to make people think twice before deciding to buy a fuel-inefficient car than merely ratcheting up fuel duty".

"Reforming VED to target the purchase of new cars, with steeply graduated rates will bear down on the wealthy," he insisted.