Production of the commonest man-made greenhouse gas carbon dioxide was also up, by 1.25 percent year on year, mostly because power stations switched to high-carbon coal from gas because of higher gas prices.

Britain claimed two weeks ago "international landmark" proposals to introduce legally binding emissions targets.

"While these figures are provisional, they underline why concerted effort to tackle climate change, both from Government and wider society, is absolutely critical," said environment minister David Miliband.

"Any increase in carbon dioxide emissions is worrying."

The figures were based on emissions from Britain, and excluded emissions cuts overseas that UK companies had funded to help them meet targets under the European Union's emissions trading scheme.

Under its Climate Change Bill earlier this month, the government proposed a legally binding target of a 60 percent reduction in carbon dioxide emissions below 1990 levels by 2050.

Britain is still on course to meet its obligations under Kyoto to cut greenhouse gas emissions by 12.5 percent on 1990 levels by 2012.

"We're still on track to almost double our Kyoto commitment, with an estimated 23.6 percent reduction in greenhouse gas emissions on 1990 levels by 2010, and we expect the long-term downward trend to continue," said Miliband.

Net carbon dioxide emissions rose to 560.60 million tonnes in 2006, but were down 5.25 percent from 1990, according to the preliminary government data.