A call for rich nations to slash greenhouse gas emissions by 2020 may be "too ambitious" to include in an international statement on climate change, the U.N. chief said Wednesday, strengthening a U.S.-led drive to remove them from the text.
Drafts of a final statement at a U.N. global warming conference this week have included guidelines for industrialized countries to consider cutting emissions blamed for rising temperature by between 25 percent and 40 percent.
U.N. Secretary-General Ban Ki-moon, however, said such goals - demanded by the European Union and developing nations - might have to wait for subsequent negotiations, though at some point targets for emissions cuts would be necessary.
"It may be too ambitious if delegations would expect to be able to agree on target of greenhouse gas emission reduction," he said.
The EU and developing nations strongly favor the guidelines, which they say are required to avoid a devastating rise in world temperatures above 2 degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels.
But the US opposed including such language in the final document would prejudice negotiations over the next two years aimed at crafting a new global warming pact to take effect in 2012.
Harlan Watson, United States senior climate negotiator told delegates "once numbers appear in text it predetermines outcomes and it will tend to drive the negotiations in one direction."
Speaking on the EU panel, Germany's Environment Minister, Sigmar Gabriel said he wanted a commitment to targets aimed at reducing greenhouse gas emissions.
He described he found a lack of direction "difficult" and questioned how a roadmap could be implemented "without having a target, without having a goal."
Negotiations on how to tackle climate change intensified as ministers and heads of state from around the world arrived at the conference.
In a series of speeches, international world leaders urged other countries to quickly impose deep cuts in greenhouse gas emissions or risk environmental and economic disaster.
Ban and other leaders laid out the basic parameters of an agreement: that rich nations, as the prime drivers of global warming, should make the first cuts in emissions and help poorer countries develop in a clean way with technology and assistance.
Fast developing nations, such as China, were asked by leaders to rein in high levels of pollution.
The conference, ending on Friday, is tasked with setting an agenda and deadline for negotiations leading to a global warming pact to succeed the Kyoto Protocol at the end of 2012.
The Kyoto Protocol commits 36 industrialized nations to reduce greenhouse emissions by an average of 5 percent between 2008 and 2012, but the pact has been severely weakened by Washington's refusal to join.
The US is the top emitter of such gases, though some say it has been overtaken by rapidly developing China.
However, even Kyoto supporters concede that the protocol is not enough and stricter measures need to be taken as soon as possible, to stop a destructive rise in world temperatures.
The meeting follows a year of high-profile scientific reports warning of rising seas, droughts and melting ice-sheets because of rising temperatures.