The first decade of this century is "by far" the warmest since instrumental records began, say the UK Met Office and World Meteorological Organization.

Their analyses also show that 2009 will almost certainly be the fifth warmest in the 160-year record.

Burgeoning El Nino conditions, adding to man-made greenhouse warming, have pushed 2009 into the "top 10" years.

The US space agency Nasa suggests that a new global temperature record will be set "in the next one or two years".

World Meteorological Organization (WMO) and Met Office scientists have been giving details of the new analysis at the UN climate summit in Copenhagen.

The WMO said global temperatures were 0.44C (0.79F) above the long-term average.

"We've seen above average temperatures in most continents, and only in North America were there conditions that were cooler than average," said WMO secretary-general Michel Jarraud.

"We are in a warming trend - we have no doubt about it."