PARIS: France's new carbon emission tax, due to have gone into effect tomorrow, has been ruled illegal by the country's constitutional court because it exempted too many polluters.

The Conseil Constitutionnel struck down the tax on Tuesday because the exemptions breached ''the principle of [tax] equality''.

It estimated that 93 per cent of industrial emissions outside of fuel use, including those of more than 1000 of the country's most polluting industrial sites, would be exempt from the tax of €17 ($27) a tonne of emitted carbon dioxide.

The ruling is a blow for the President, Nicolas Sarkozy, as the measure was one of his flagship initiatives to cut emissions. It also leaves the Government with a €4.1 billion hole in its 2010 budget.

Meanwhile, the President of Brazil, Luiz Inacio Lula da Silva, has signed a law requiring that Brazil cut its projected greenhouse gas emissions by 39 per cent by 2020, meeting a commitment made at the Copenhagen climate change summit.