About one hundred and eighty countries are attending a meeting in the Argentine capital, Buenos Aires, to try to define how they will reduce emissions of harmful greenhouse gases.

The levels of the cuts were established last year in the UN Climate Change treaty signed at Kyoto in Japan, but discrepancies have arisen as to how they are to be achieved.

Japan and the United States want to be allowed to reduce their emissions by less than the agreed amount and to pay other nations to cut theirs more.

European countries insist there must be a limit to this trade in emissions if the Kyoto Protocol is to be respected.