Attempts to forge a road map for a new international climate change agreement are entering the endgame amid accusations the US is trying to wreck the deal.

On the last day of the United Nations conference in Bali, ministers are trying to agree to launch negotiations on a global emissions reductions agreement which will replace the current Kyoto Protocol when it expires in 2012.

After the US proposed text in the road map which appears to lay out an agenda for voluntary rather than compulsory emissions reductions, environmental groups accused the country of destroying hopes of a global deal.

But the ploy may just be a negotiating tactic as countries jockey to get their proposals into the road map before attempting to get it agreed by ministers from more than 180 nations gathered in Bali.

The EU wants to see formal negotiations launched with an end date of 2009 for signing a deal, and has been pushing for mention of a science-based target of 25% to 40% emissions cuts for developed countries.

Europe increased the pressure on America by saying it would be meaningless to attend a US-led climate change summit for major economies next month to discuss emissions if an "ambitious" plan is not agreed in Bali.

The US has repeatedly said it does not want to see figures in the text, because it says it might "prejudge" outcomes - and has now proposed much weaker language for the road map.

Environment Secretary Hilary Benn, speaking in the middle an intense schedule of meetings, said: "The hard bargaining has begun.

"If the negotiation is to be successful, we need two things: we have to accept the science and we have to clear about what every country will contribute."

But he said: "There's real desire to get an agreement. The world will not forgive us if we don't."