The European Union may raise its greenhouse- emissions-cut target to 26 per cent in a bid to overcome deadlock at a UN Climate Change Conference in Copenhagen, EU sources said Wednesday, DPA reported.

The 27-member bloc has already promised to reduce its emissions by 20 per cent below 1990 levels by 2020.

Prior to the start of the Copenhagen conference, it said it would raise its target to 30 per cent, but only if other major polluters came up with comparable offers.

The United States has so far offered a 17-per cent cut against 2005 levels. However, an earlier base year implies deeper cuts. But US negotiators say their longer term targets are far more ambitious.

The improved EU offer would involve an unconditional cut of 25 or 26 per cent by 2020, or 30 per cent by 2025.

Britain and France had been among the EU countries pushing for an unconditional 30-per cent offer in Copenhagen.

Speaking to the BBC earlier on Wednesday, British Prime Minister Gordon Brown said the Copenhagen talks faced "huge" but "not insurmountable" challenges.

The British premier also urged all sides to help seal a deal by Friday.

"We can't do it on our own, it's about the whole world coming together," Brown said.