China, India and their allies in the Third World were in open revolt at the UN climate summit in Copenhagen today as police fired tear gas and made at least 200 arrests to head off a march on the conference venue by environmental activists.
As world leaders including Robert Mugabe and Hugo Chavez flew in for the final three days of the conference, the Danish Prime Minister Lars Lokke Rasmussen personally took charge of the negotations for a global climate accord.
But he immediately faced concerted interventions from the floor, led by China's Vice Foreign Minister, He Yafei, at a decision to publish two new negotiating texts designed to move the process up a gear.
As conference hosts, the Danes have the task of ensuring that the Copenhagen summit ends in a meaningful deal, but developing nations have accused Mr Rasmussen of trying to impose a deal.
Clashes as protesters try to storm Copenhagen summit
They also fear that he is trying to negotiate an entirely new treaty to supersede the Kyoto Protocol, under which only developed countries have to reduce their carbon emissions.
Within minutes of taking over as chair, Mr Rasmussen reminded delegates that their leaders were arriving and expected progress to be made. "I think the world is expecting us to reach some kind of agreement regarding climate change, not just discussing procedure, procedure, procedure.
"We have to move everything forward."
To loud applause, and in perfect English, Mr He responded: "Thank you Mr Chairman. I think the matter is not just procedural, procedural, procedural. Actually it's substantial: it's a question of respect for the host for at least 192 parties. You can't just put forward some text from the sky."
As the world leaders arrived in Copenhagen - Gordon Brown flew in last night - thousands of protesters made a concerted attempt to breach security at the Bella Centre, the sprawling conference venue in the outskirts of the city.
But they were stopped at police barricades and scuffles soon broke out as police corralled the protesters. A police spokeswoman said that at least 200 demonstrators had been arrested by noon.
A Times reporter who was trapped with a group of around 2,000 protesters in a police tactic known as "kettling" said that officers were charging demonstrators and using pepper spray to break them up. Danish police have arrested hundreds of people over the past week and have been accused of being unnecessarily heavy-handed.
There were touches of humour. A group of about a dozen Danes wearing white ties and sipping champagne held an ironic counter-protest, calling on the police to arrest the climate activists. The called themselves Lobbyists for a Profitable Climate Solution.
Several hours into the demonstration, a group of five UK activists deployed eight inflatable mattresses to create a pontoon bridge across a canal which runs about 400m from the Bella Centre. They sat on the mattresses, throwing sausages at the police dogs on the bank opposite.
One of them told The Times: "Obviously it's a purely symbolic act. A piece of theatre."
As the assembled leaders began to deliver "national statements" that will take up the next two days, the negotiations moved into top gear.
The conference chair, the former Danish climate minister Connie Hedegaard, told delegates that she would be stepping down and handing over the chair to Mr Rasmussen.
But Ms Hedegaard will remain in charge of the informal negotiations, from which any accord will emerge. She told delegates that two new negotiating texts were about to be published that would point the way forward to a political deal to be signed on Friday.
"It really is crunch time," one delegate said. "The game is on."
Mr Brown arrived at the conference last night, the first major world leader to do so, and met Kevin Rudd, the Australian Prime Minister, at a Copenhagen hotel. Both he and Mr Rudd - who is actively involved in the negotiations as a "friend of the chair" - warned that a deal was not guaranteed.
The Prime Minister met the UN Secretary-General Ban Ki Moon this morning and had a full slate of bilateral meetings during the day to try to sort out the long-term financing of an agreement.
By the end of the day, about 100 world leaders are expected in town, including Mr Mugabe, Binyamin Netanyahu, the Israeli Prime Minister and President Nicolas Sarkozy of France.
But President Obama, whose accord will be crucial if the summit is to come up with a meaningful agreement that could be translated into a binding international treaty next year, will not arrive until Friday and has left it to officials to hammer out an accord on how much the United States will reduce its emissions and how much it will be allowed to offset its emissions on the global carbon market.