"The central aspect of the negotiations now is the envelope on the amount of money that is needed to accelerate the freezing (and) phase-out of HCFCs (Hydrochlorofluorocarbons)," UNEP spokesman Nick Nuttall told AFP.

"I would not characterize it as a major obstacle or hurdle but there is still debate about whether the money is actually on the table from the developed countries for the developing countries," he said.

An estimated 150 million dollars per year is needed to replenish an existing fund beyond 2008 to help countries switch to new technologies and chemicals that do not deplete the ozone, said delegates.

Others want assurances an amendment to the 1987 Montreal Protocol would not devastate industries facing unique circumstances, Nuttall said.

South Africa, for example, relies heavily on HCFCs to cool its gold mines and refuses to interrupt mining while waiting for new specialized air conditioning technologies to be rolled out.

"They need to know that this is not going to be interrupted by an agreement here," Nuttall said.

"The discussions are about financial aspects and reassurances that if you do get an accelerated freeze and phase-out, certain countries' economic or industrial positions (are taken into account)," he said.

The current calendar calls for developed countries to stop using anti-ozone compounds found in many refrigerators, fire retardants and hairspray by 2030, and for developing nations to follow suit by 2040.

But the United States and the European Union, backed by UNEP, want to see 10 years trimmed off that timetable after discovering that patching up the ozone layer will also help tackle global warming.

Delegates of 190 countries, including more than 70 environment ministers, are meeting in Montreal this week to mark the 20th anniversary of the first treaty to protect Earth's stratospheric shield and to hammer out a new agenda.

Despite the sluggish pace of negotiations, Nuttall commented, "We're optimistic that we will get a deal on Friday."

"It's a golden opportunity and a golden opportunity that does not come around very often. If it's not taken by countries this week, we may lose that golden opportunity forever," he said.

The Montreal Protocol, adopted in September 1987, was designed to heal the gaping hole in the blanket of oxygen molecules that protects animal and plant life from the Sun's dangerous ultraviolet rays.

The atmospheric wound, which last year was estimated to span a record 29.5 million square kilometers (10.81 million square miles) over and beyond the Antarctic, is believed to be caused by slowly degrading pollutants in the air.

Ninety-five percent of targets for older CFCs (chlorofluorocarbons) elimination by 2010 have already been met.

But some 88,000 tons of ozone-depleting substances are still produced every year, 85 percent of them in the industrialized world. And experts estimate that an additional 10,000 to 15,000 tons are produced illegally.

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