Prime Minister Stephen Harper may be staying in Copenhagen longer than expected, as world leaders make a last-minute push for an agreement at the UN climate talks.

World leaders had failed to hammer out an agreed-upon climate deal by late Friday, which reportedly led United Nations Secretary-General Ban Ki-moon to request that delegates and world leaders remain in the Danish capital.

A Harper spokesperson said the Canadian delegation had not been "formally asked to stay," though CTV's Ottawa Bureau Chief, Robert Fife, reported that it is likely they will stay overnight if talks continue.

Earlier Friday, U.S. President Barack Obama arrived in Copenhagen, where he attended an emergency meeting with 19 other leaders. Intending to use his influence to get a deal done, this early attempt was unsuccessful.

Australian Prime Minister Kevin Rudd, British Prime Minister Gordon Brown, German Chancellor Angela Merkel and French President Nicolas Sarkozy were among the attendees. Chinese Premier Wen Jiabao chose not to attend the high-level meeting, sending an envoy in his place.

Harper was not at the meeting as he was not on the guest list. A spokesperson for the prime minister said the list of countries invited to the meeting had been compiled for Obama's people as a representative mix of regions and carbon emitters.

Following the meeting, Harper had a brief audience with Obama over lunch.

The prime minister has kept a low profile in Copenhagen since arriving earlier this week.

On Thursday night, Environment Minister Jim Prentice addressed the UN climate talks instead of Harper, while the prime minister attended a royal dinner hosted by the Queen of Denmark.

Also Friday, Canada was stamped with the "Colossal Fossil" designation, a dubious honour given to the country by environment groups which rank its greenhouse gas target as being "among the worst in the world."

Divisions in Copenhagen

The talks in Copenhagen have been marred by a growing divisions between rich and poor countries, as well as between the United States and China -- the world's two biggest polluters. Delegates blamed the rival countries for the lack of a political agreement all nations were expected to sign earlier in the day.

The Chinese and U.S. leaders also failed to announce any new commitments on slashing their greenhouse gas emissions.

Wen and Obama met privately on two occasions Friday, as world leaders pressed to salvage the summit.

Abandoning hope of a comprehensive deal, a group of about 25 countries tried to agree on a two-page political statement that would lay out critical elements. It called for spending $30 billion in the next three years to help poor countries cope with climate change, spending that would ramp up to $100 billion per year by 2020.

As talks continued, new drafts of the same document -- titled the Copenhagen Accord - added clauses that evolved during the day. Later drafts said rich countries should cut their emissions by 80 per cent by the year 2050.

A separate group of leaders worked on a potential deal involving emission cuts that UN Environment Program Director Achim Steiner said was "doable."

He put the odds of a meaningful deal at better than 50-50 when speaking with The Associated Press about the progress made on the final day of the UN climate conference.

With files from The Canadian Press and The Associated Press