German Chancellor Angela Merkel said today she would only attend December's crunch climate conference in Copenhagen if the US, China and India first make clear their negotiating positions.
"The European Union has developed clear and unambiguous negotiating positions. We now want contributions from the US and from countries like China and India," Merkel said in the first major policy speech of her second term.
"I will make a special personal effort to achieve this. And of course if it is successful, yes, I will go to Copenhagen," Merkel said.
She added: "A failure of the world climate conference in Copenhagen in December would set international environmental efforts back by years. We cannot afford this.
"A substantial political agreement is indispensable in order to create conditions for a binding international protocol for after 2013. Time is pressing."
The aim of the Copenhagen summit is to hammer out an accord for 2013 onwards that will include emission cuts and aid to help poorer countries develop low-carbon economies and deal with the ravages of climate change.
Forty heads of state or government, including British Prime Minister Gordon Brown and French President Nicolas Sarkozy, have indicated they will attend the climax of the December 7-18 talks in the Danish capital.
But with signs growing that the get-together will fall short of achieving a binding, historic pact, it is unclear whether other leaders, most notably US President Barack Obama, will show up.