Britain's poorest families are most likely to lose out if taxes on energy use are introduced, according to a new study.

A report published on Wednesday by the Joseph Rowntree Foundation found poorer households are spending more of their income on energy costs than the better off.

The analysis was welcomed by the Liberal Democrats, even though the party has backed the introduction of more green taxation as a key way of protecting the environment.

Environment spokesman Norman Baker said the party was committed to support systems that would alleviate the impact of new taxes for less well off families.

According to the report, consumption of energy, water and waste disposal services in poorer households is disproportionately high in relation to their income.

As a result, any flat rate environmental taxes or charges would take a greater share of income from poor people than from the better-off.

Most unintended social consequences could be dealt with by targeting green taxes on the better off or providing support for low-income groups, said authors Professor Paul Ekins and Dr Simon Dresner of the Policy Studies Institute.

But they also warned that the use of environmental resources varies widely within income groups.

"This means that even if most low-income households were to be protected by charging or compensation schemes, a minority would still end up as net 'losers'," said the report.

Carbon tax

On energy use, it would be possible to introduce a carbon tax that would, on average, benefit poor households.

But none of the existing compensation packages reviewed for the report were able to bring down the proportion of losers among the poorest tenth of households to much below 20 per cent.

A preferred measure was taxation based on property, with varying council taxes or stamp duty used to encourage energy savings.

"The results from this research can help policy makers ensure that, if environmental taxes and charges are introduced, they are designed in ways that prevent unintended consequences for people who live on low incomes," said Professor Ekins.

"Our research demonstrates that, in general, it is possible to solve the disproportionate impact on poorer households sometimes associated with environmental taxes and charges."

Debate urged

The Liberal Democrats said the government had dodged the debate on environmental taxation.

"Today's report is welcome as it acknowledges the value of using economic incentives to encourage good environmental behaviour - a long-standing Liberal Democrat principle," said Baker.

"In September the Liberal Democrat Party conference endorsed a range of economic measures to reward good environmental behaviour and punish damaging behaviour.

"The report is right to recognise the impact that new or different taxes can have on the poorest in society. But in assisting poorer families we must not compromise our environmental goals.

"Instead we must look at alternative support systems as well as tackling the underlying causes of fuel poverty by promoting energy efficiency."

But Professor Ekins cautioned that "any broad but practicable compensation scheme will still create net losers among low-income households".

"But in practice, households will also have the option of responding to the new tax or charge by cutting their consumption of the resource being taxed, further reducing the number of net losers," he added.

"Further targeted compensation measures should be able to prevent unacceptable hardship among those who remain."