The United Nations official in charge of talks on climate change believes there is little chance of reaching a binding agreement to tackle global warming by the end of this year.
Yvo de Boer was speaking at a meeting in the German city of Bonn on how to make progress on the Copenhagen climate accord ahead of the next major UN summit.
The talks were again hampered by rifts between developed and developing nations, the BBC reports.
Many developing are still angry about the way the summit in Copenhagen in December concluded.
Analysts are showing that the pledges the countries made in the Danish capital to curb carbon emissions are unlikely to keep the global average temperature rise below 2 degrees celsius.
There is anger too that the United States and possibly the European Union are limiting climate aid money to countries fully signed up to Copenhagen's outcome, the BBC reports.
Despite their differences, governments agreed on a timetable and a procedure for the year's talks, which will culminate in a summit in Mexico.