Copenhagen, Dec 19 (DPA) The leaders of the world's biggest economies reached what even its authors described as an insufficient deal aimed at slowing global warming after 11th-hour discussions in Copenhagen early Saturday.

The agreement, brokered by the US and China, backs scientists' call to limit global warming to within 2 degrees centigrade against pre-industrial levels.

But it contains no improved targets on greenhouse gas emissions from rich nations and does not commit anyone to a legally binding cuts. Attempts to reach an effective treaty will now be taken up next year.

While it was endorsed by other big players such as the European Union, India and South Africa, the so-called Copenhagen Accord was rejected by smaller UN members such as Sudan, which during the conference acted as the chair of the G77 group of developing nations.

Hours after the deal was announced, delegates debating the agreement early Saturday were in an uproar in the assembly with some threatening to reject the accord. It had powerful backers, however.

"Today we've made a meaningful and unprecedented breakthrough here in Copenhagen," US President Barack Obama asserted at the end of a 12-day UN conference on climate change.

At the same time, "we know that this progress alone is not enough," Obama said.

"A deal is better than no deal," said Jose Manuel Barroso, head of the EU's executive arm, the European Commission.

"What could be agreed today falls far below our expectations, but it keeps our goals and ambitions alive," Barroso said.

Environmentalists expressed unanimous criticism of the deal, which was sealed by an exclusive club of countries during closed-door discussions that turned almost 100 other heads of state and government into hapless bystanders.

"After years of negotiations, we now have a declaration of will which does not bind anyone and therefore fails to guarantee a safer future for future generations," said Kim Carstensen, who heads WWF's Global Climate Initiative.

The closed nature of the talks angered many delegates, particularly the leftist-ruled countries of Latin America. Venezuela, Bolivia, Nicaragua and Cuba said they planned to oppose the accord, which must be approved by the 193-member plenum.

Venezuelan delegates spoke of a "coup" against the spirit of the UN while Bolivian officials described as "dictatorial" the way in which the accord was presented to the delegates shortly before the vote on it.

Countries most at risk from climate change, such as Tuvalu and the Maldives, wanted the 2-degree threshold to be lowered with Sudan arguing that such a limit would still mean death and a "holocaust" for many Africans.

As part of the accord, rich nations agreed to quantify the amount of aid they were willing to give to poor nations to help them reduce their emissions and cope with the consequences of climate change.

Immediate, "fast-start" aid was quantified at $30 billion over the next three years, with the EU and Japan pledging around $11 billion each, and the US offering $3.6 billion.

Rich nations also set themselves the goal of "mobilizing $100 billion a year by 2020 to address the needs of developing nations".

One of the most controversial issues standing in the way of a deal between the US and China - which together account for about 40 percent of global emissions - hinged on the question of how much right third countries should have to inspect each other's greenhouse-gas emission claims.

While Obama had called for "transparency" in the way emission targets should be monitored and reported, China strongly opposed any international exercise that would infringe on its national sovereignty.

The Copenhagen Accord states that "provisions for international consultations and analysis" should take place under "clearly defined guidelines that will ensure that national sovereignty is respected."

Apart from the final-day drama, the Copenhagen conference registered deep divisions and finger-pointing throughout its duration.

Disagreements emerged both among developing and developed countries.

The EU accused both the US and China of not doing enough to cut their emissions while poor African states and low-lying island states at risk of being submerged by rising sea levels blamed the rest of the world.

The overarching aim of the Copenhagen summit was to endorse the scientific view that a rise in average temperatures of more than 2 degrees would have terrible consequences on the world's climate, causing rising sea levels, droughts and storms.

In his speech to the conference, Obama reminded his colleagues that climate change was no longer "fiction" but "science," and urged them not to waste any more time in fruitless talks.

But with legislation still pending in the US Senate, Obama refused to go beyond a previous commitment to cut his country's emissions by in the range of 17 percent by 2020."