LONDON - Britain will miss by a large margin its own goal of cutting carbon dioxide emissions by 20 percent from 1990 levels by 2010 and must make far greater efforts, Environment Secretary Hilary Benn said on Tuesday.

Giving evidence to parliament's all-party Environment Audit Committee, Benn said the actual figure in 2010 was likely to be a 16 percent cut -- and that only with a significant quantity of carbon emission credits purchased overseas.

"We will not be achieving the target we have set but it is still real progress," he said, defending the efforts the government has been making.

"We are not making fast enough progress on carbon reductions. We have got a long, long way to go. We have a very big task on our hands," he said, highlighting the Climate Change Bill now going through parliament.

The Bill, which the government hopes will become law within six months, sets a target of cutting carbon dioxide emissions by 26-32 percent from 1990 levels by 2020 and 60 percent by 2050.

But Benn and Prime Minister Gordon Brown have both said they will ask for an independent climate change monitoring committee to be set up by the bill to look at the possibility of raising the end target to 80 percent.

He acknowledged that extra measures would be necessary to obtain the necessary cuts in emissions of climate warming carbon gasses from burning fossil fuels for power and transport, but declined to go into detail.

Pressed on whether it was right for a country to be able to buy carbon credits from abroad to make its own performance look better, Benn said that it was a global problem so the solution had to be equal in scope.

As long as the foreign carbon credits were verifiable reductions in emissions, they were acceptable as part of a national performance evaluation, he added.

Benn, who will go next week to a meeting of UN environment ministers on the Indonesian island of Bali to discuss a possible future global carbon cut package, said it was vital the meeting agreed the format for future talks to end in December 2009.

"We have got to get on with it," he said, noting that the biggest risk was of countries refusing to participate in any accord to tackle climate change after the Kyoto Protocol on cutting carbon emissions expires in 2012.

On the other hand, the biggest spur was the fact that the science of human-induced climate change was now irrefutable as was the fact that there was only one planet Earth on which to live.

Scientists predict that average temperatures will rise by between 1.8 and 4.0 degrees Celsius this century because of global warming, causing floods, droughts and famines, raising sea levels and putting millions of lives at risk.