Copenhagen, Dec 9 : Climate change talks in Copenhagen entered their third day Wednesday amid concerns of a widening rift between developed and developing nations and looming protests by extremists.

Despite initial optimism about a possible deal on slowing global warming, negotiators remain entrenched in their positions, with rich nations demanding bigger efforts from the developing world and emerging economies refusing to do more.

"Developed and developing countries shoulder different responsibilities," said China's chief negotiator, Su Wei.

The north-south divide was highlighted Tuesday by the publication of a Danish text, drafted by the Danish prime minister's office and circulated among a restricted group of delegations attending the UN talks.

The draft, published on the Guardian newspaper's website, envisages a controversial deadline for emissions from developing nations to peak.

It also calls for financial support from rich nations to prioritise "the poorest and most vulnerable countries", rather than all developing nations.

"This text goes against everything we have been working for before this summit," said Lumumba Stanislaus Di-Aping, Sudan's UN ambassador, who represents developing nations in the Group of 77 and China during the Copenhagen talks.

Di-Aping openly accused Danish Prime Minister Lars Lokke Rasmussen, the meeting's host, of taking sides.

"It is most unfortunate that the person who is supposed to lead negotiations in a balanced way is breaking our trust and is instead protecting the interests of the rich countries," he said.

Meanwhile, Danish security forces were bracing themselves for a weekend of protests by possibly tens of thousands of demonstrators.

Though part of the European Union's free-movement Schengen area, Denmark re-introduced police checks on its border with Germany Tuesday in a bid to prevent violent demonstrators from abroad from reaching the Danish capital.

A group of left-wing militants which calls itself Never Trust A Cop plans to demonstrate outside a business conference in downtown Copenhagen rather than target the heavily-guarded Bella Center venue of the climate change talks, which is located in the city's outskirts.(DPA)