Minister Lars Lokke Rasmussen.
"This is not about procedure, this is a matter of substance," retorted China's chief negotiator Wei Su.
Organisers were forced to issue a statement after some media outlets erroneously reported that the conference's chairwoman, Connie Hedegaard, had resigned.
With more than 30 world leaders slated to address the conference later in the day, Rasmussen was entrusted with conducting talks among environment ministers, while Hedegaard was to lead informal consultations.
As a consequence of the unprecedented number of heads of state and government who have started to arrive in Copenhagen to participate in climate negotiations, Danish Prime Minister Lars Lokke Rasmussen will, from the beginning of the High-Level Segment, take the chair as president, organisers said.
A restricted group of 25 countries, among them Britain, Germany and four other European nations, were to discuss ways of helping the conference's chair break the impasse, German Environment Minister Nobert Roettgen explained earlier in the day.
Roettgen said major problems remained between the Danish presidency of the conference and the G77 group of developing nations, which includes big countries like India and China, but also smaller nations from Africa.
Meanwhile, delegates were keeping a close eye on new compromise texts, due to be presented shortly and aimed at overcoming the negotiating deadlock.
"We are extremely disappointed at the lack of progress," said a delegate from Tuvalu, whose Pacific island state risks being submerged by rising sea levels as a result of global warming.
"I have the feeling of dread that we are on the Titanic, and that we are sinking fast," he said.
The UN talks aim to keep global warming in check by demanding massive greenhouse gas emission cuts from rich countries and billions of dollars in aid to the developing world.
The European Union (EU) was considering raising its target on emissions cuts to 25 percent in a bid to encourage other parties to step up their efforts, EU sources told DPA.
The 27-member bloc has already promised to reduce its emissions by 20 percent below 1990 levels by 2020.
Prior to the start of the Copenhagen conference, the EU said it would raise its target to 30 percent, but only if other major polluters came up with comparable offers.
The US has so far offered a 17-percent cut against
2005 levels. However, an earlier base year implies deeper cuts. But US negotiators say their longer term targets are far more ambitious.
The improved EU offer would involve an unconditional cut of 25 or 26 percent by 2020, or 30 percent by 2025, according to the German edition of the Financial Times.
Britain and France had been among the EU countries pushing for an unconditional 30-percent offer in Copenhagen.
Speaking to the BBC earlier Wednesday, British Prime Minister Gordon Brown said the Copenhagen talks faced "huge" but "not insurmountable" challenges.
Brown also urged all sides to help seal a deal by Friday.
"We can't do it on our own, it's about the whole world coming together," Brown said.
Security was high at the Bella Centre, where Brown was to join Zimbabwean President Robert Mugabe and more than 30 other heads of state and government due to give speeches on Wednesday.
Outside, police in anti-riot gear erected concrete barriers aimed at preventing thousands of activists from storming the conference's venue.