Speaking at a sustainable development forum in Paris before flying to a landmark UN climate conference in Montreal, Ollin said more needed to be done.

The 1997 Kyoto protocol finally became operational on Wednesday when 34 signatory countries at the UN Framework Convention on Climate Change agreed to a regulatory structure for reducing greenhouse gas emissions.

But the United States, fearing restrictions could devastate its energy-hungry economy, has refused to ratify the treaty that does not require developing countries to cut emissions.

"We cannot rest there," said Ollin.

"The key factor is managing to create engagements beyond 2012 bringing in the United States and the big developing countries (China, India, Brazil and Mexico)."

Air transport and maritime shipping, which were not part of Kyoto but "representing nevertheless a growing part of emissions" should also be included in the protocol, Ollin said.

Carbon dioxide emissions from Europe's aviation sector grew 60 percent between 1990 and 2002, according to a recent International Energy Agency report.

European Union partner Germany will also lobby for an extension of the protocol in Montreal, the country's environment minister, Sigmar Gabriel, said in an interview with a German newspaper published Saturday.

US delegates have taken a hardline at the 12-day Montreal conference, which ends on December 9, saying they oppose any discussions of objectives or a timetable for reducing emissions post-2012 when the Kyoto treaty ends.

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