The pact requires developed countries to cut greenhouse gas emissions blamed for causing climate change by an average of five percent of 1990 levels by 2012.

Ministers officially take the reins of negotiations on Wednesday and were expected to finalise the agreement on Friday.

But key questions remained over whether enough countries would find the rules acceptable and agree to ratify the pact, known as the Kyoto Protocol, bringing it into legal force.

"All participants have made considerable progress," said Japan's ambassador for international affairs Kazuo Asakai.

But he stressed at a news conference: "We will need to collectively redouble our efforts so that by the end of Friday we have a successful agreement...which will pave the way for ratification by Japan and by as many countries as possible."

The United States was not going to be among them. President George W. Bush said the Kyoto Protocol, named after the ancient Japanese capital where it was agreed in 1997, would hurt the U.S. economy and was unfair as it excluded developing countries.

WASHINGTON STILL REVIEWING POLICY

Washington is still reviewing its policy on combating climate change which United Nations scientists say could raise average temperatures by almost six degrees Celsius this century with disastrous consequences such as floods and droughts.

Despite Bush's position, the rest of the world at a meeting in Bonn in Germany in July agreed in principle to push ahead.

But, as time ran out, they left the legal drafting of the detailed rules to the talks now taking place in Morocco which has thrown up a number of potential pitfalls.

Questions such as whether sanctions against countries failing to meet their target should be legally binding, and flexible rules on emissions trading - buying and selling the right to pollute - have emerged as possible crunch issues.

The European Union said the Bonn accord was enough for its 15 members to ratify the pact and has begun the legal procedure.

Belgian Energy Minister Oliver Deleuze, who is leading the EU delegation, said he would not renegotiate the Bonn accord.

"No, no more than we renegotiated Kyoto at Bonn," he told reporters. "Otherwise, what will we be renegotiating next time - the Marrakesh agreement?"

JAPAN, RUSSIA WAIT

Without the United States, the world's biggest emitter of carbon dioxide, the main greenhouse gas, other big industrialised nations must ratify to bring the pact into force.

But Japan and Russia, which negotiate together in the so-called umbrella group which used to include the United States, said yesterday any decision to ratify Kyoto would depend on an acceptable outcome from Marrakesh.

Over the weekend Japanese government sources had said Tokyo was already preparing ratification, but Asakai told reporters in Marrakesh: "Our decision on ratification will depend on the result of COP7 (the Marrakesh conference)."

Russian negotiator Alexandre Bedritsky said: "Only after the documents on mechanisms (like emissions trading) are adopted will Russia be in a position to start considering the question of ratification of the Kyoto Protocol."

Environmental groups, which have singled out Russia as the bad guy in Marrakesh, wrote an open letter to President Vladimir Putin saying the Russian delegation was backtracking on a commitment Putin made to the EU to work towards ratification.