Despite all-night efforts by delegates to hammer out a deal at the Copenhagen Climate Change summit, Barack Obama has warned that talks could yet end in deadlock.

The US president arrived in the Danish capital city this morning (December 18th 2009) in time for the final day of negotiations, with the conference so far hit by in-fighting between international policymakers and angry protests from activists outside the venue.

Mr Obama said that the ability for nations to take collective action on tackling global warming and its effects is currently in doubt.

"We are running out of time. The time for talk is over. It is better for us to act than to talk," he stated.

"The question is whether we move forward together or split apart."

His comments follow the announcement by US secretary of state Hillary Clinton that the US would pay into an international fund to help developing nations fight the effects of climate change.

The proposal will amount to $100 billion (£62 billion) of investment a year by 2020.