The world’s poorest countries, inundated by rising seas and worsening disasters, made a last ditch plea for financial help early Saturday as negotiators at United Nations climate talks struggled to reach an ambitions deal to combat global warming.

The two-week U.N. conference in the Qatar capital of Doha was never meant to yield a global climate pact to curb emissions of greenhouse gases — that has been put off until 2015. But many developing nations said they were increasingly frustrated with the lack of ambition from rich countries on everything from climate aid to the emissions cuts they will make until 2020.

Talks were set to end Friday but they continued into early Saturday with negotiators set to meet in several hours to assess progress.

“The expectations we had for a great deal in Doha is no more. That is dust,” said Mohammed Chowdhury, a Bangladeshi who is a lead negotiator for a coalition of poor nations called the Least Developed Countries or LCD.