By MARTIN DELGADO

Last updated at 00:13 16 December 2007

He is known as the "hard man" of climate-change negotiation.

But after 12 exhausting days of trying to reach a worldwide agreement on reducing greenhouse gas emissions, it was suddenly all too much for Yvo de Boer.

As the 200-nation Bali conference wrangled over a minor procedural matter, the Dutch diplomat in charge of the talks burst into tears and had to be led away by colleagues.

Scroll down for more ...

Moments earlier, Mr de Boer had been warning delegates that failure to reach an agreement on global warming could "plunge the world into conflict".

Officials from China, which feels Western countries should do more to reduce their greenhouse gas emissions, accused UN negotiators of ignoring conference protocol.

Mr de Boer, distinctively dressed in a floral shirt, stepped up to the microphone to defend his staff - only to find that the words would no longer come.

As his unfinished sentences trailed away, he broke down and walked off the platform to supportive applause.

"He wasn't just wiping his eyes, he was in floods of tears," said one observer.

"Three colleagues - one of them a woman - formed a protective group around him and escorted him out of the hall. It was all very dramatic."

Mr de Boer's breakdown came after nearly a fortnight of squabbling over proposals to cut carbon emissions.

The European Union went to the conference demanding that industrialised nations commit to cuts in CO2 emissions of 25-40 per cent by 2020, a stance which was strongly opposed by the US, Canada and Japan.

America's representatives had also been jeered for insisting on firmer commitments from developing countries --despite President Bush's refusal to sign up to the previous targets laid down in the Kyoto Protocol in 2001.

In the end, a compromise was reached with a text that did not mention specific targets but acknowledged that "deep cuts in global emissions will be required".

A wave of relief swept the hall as US delegation chief Paula Dobriansky finally declared: "The United States is very committed to this effort and just wants to really ensure we all act together.

"With that, Mr Chairman, let me say to you we will go forward and join consensus."

The resulting treaty, known as the "Bali road map", sets in motion a two-year process of negotiations designed to replace the Kyoto Protocol, which expires in 2012.

Under the deal, a new pact will be agreed at a meeting in Copenhagen in 2009.

By then, members of the UN Framework Convention on Climate Change - the organisation of which de Boer is executive secretary - should have agreed on a comprehensive plan involving wealthy and developing nations.

Environment Secretary Hilary Benn hailed the Bali deal as "an historic breakthrough" and a "huge step forward" in tackling climate change.

But Prime Minister Gordon Brown sounded a note of caution. "The Bali road map agreed today is just the first step," he said. "Now begins the hardest work."

The deal will come as a relief to Mr de Boer, who is known in the Netherlands for his passionate advocacy on the subject.

His reputation as an incisive --and tireless - negotiator has earned him the "hard man" tag.

However, former colleagues said his behaviour in Bali was not entirely out of character.

Political adviser Matthijs Spits said: "We Dutch can become quite emotional --surprisingly so for other nations who think we are cold."