DURBAN, South Africa — With UN climate talks stalling and time running out, host country South Africa has suggested extending the Durban summit by “some hours or days,” Canada’s chief envoy said Thursday.

But some countries, including Canada, which has been widely criticized for quitting the Kyoto Protocol, have “hard departure plans” and would not be willing to stay past Friday, the official end of the 12-day summit, Canadian environment minister Peter Kent said in a conference call with journalists.

As climate change negotiations headed into their final day in Durban, a divide remained between the US, the EU and major carbon-emitting developing countries including China and India.

More than 190 countries are in talks on what will replace the Kyoto Protocol when its carbon-emission limits expire at the end of December 2012.

More from GlobalPost: COP 17: Canada is the bad guy at climate change talks

Todd Stern, the US special envoy for climate change, praised the progress in hammering out the architecture of the Green Climate Fund, a way for developed countries to help poor countries hard hit by climate change, with $100 billion to be mobilized by 2020.

“I think that’s going to get done. I’m confident of that,” Stern said of the fund in a briefing.

But progress on the larger issue of a binding agreement to cut carbon emissions remained deadlocked. The push at the summit is for an agreement that would seek to limit global warming to 2 degrees Celsius (3.6 degrees Fahrenheit). Environmentalists are now warning of a “4 degree future.”

The EU countries have been champions of tough emission curbs. They back a second commitment period for the Kyoto accord. EU negotiators have European public opinion behind them.

But there are major divisions between the EU, the US, and what’s called the BASIC group of developing countries – Brazil, South Africa, India and China.

The US, along with Canada, Japan and Russia, argue that any new agreement must include fast-growing developing countries, with their correspondingly fast-growing emissions. The US insists that China, in particular, must take on more responsibility for its carbon emissions.

China and the other BASIC countries insist on different standards for developed and developing countries — known as “common but differentiated responsibilities.” Complicating things further are rumors of a split among BASIC, with Brazil reportedly willing to back a legally binding deal.

More from GlobalPost: China is surprise good guy at Durban climate conference

Wendel Trio, director of Climate Action Network Europe, said bilateral meetings have been taking place between the EU countries and the US, at the Hilton hotel next to the conference center.

But major outstanding issues remain. A key one is the timeline – the issue of when negotiations on a new legally binding agreement would be finalized. Another is the definition of “legally binding.”

Some countries, including Canada, have said they are willing to accept a binding treaty that would take effect in 2015. But China has said it would only be willing to even consider a treaty for post-2020.

South Africa as host has been criticized for failing to do enough to keep talks moving forward. On Thursday, the penultimate day of the Durban summit, many countries canceled their scheduled briefings as intense talks continued.

Jimmy Manyi, spokesman for South Africa’s Cabinet, denied that negotiations were failing to progress.

“We are very optimistic as a country that there will be agreements that are made that will take us forward,” he said.

Manyi added: “We do not envision a situation where we're deadlocked.”