Pfaffenbach is also in charge of German preparations for June's meeting of G8 leaders.

"Climate change is an increasing concern. It's going to have a greater emphasis than we had originally planned," he told foreign reporters at a briefing on Wednesday.

Since 2005, around 12,000 large-scale energy consuming plants in the European Union have been able to buy and sell permits that allow them to emit carbon dioxide (CO2).

Companies exceeding individual limits can buy unused permits from firms that have come under their emission allowance. This is how the EU has been meeting its Kyoto obligations.

Pfaffenbach said the issue of what to do after the expiry of the UN's Kyoto Protocol, which binds 35 industrial nations to cutting CO2 emissions by 2012, would also come up at the summit.

"These issues will be discussed. We want to indicate a direction where we could go after Kyoto," he said, adding that G8 member the United States had still not ratified the protocol.

A United Nations panel said last week that mankind is to blame for global warming, and predicted more droughts, heatwaves and a slow rise in sea levels that could continue for more than 1,000 years even if greenhouse gas emissions were capped.

Another issue related to climate protection that might be discussed would include the idea of a "clean car," though Pfaffenbach did not offer any specifics on how such a clean car might run.

The June G8 summit in the German Baltic resort of Heiligendamm will also focus on Africa, and economic issues including global imbalances and the role of hedge funds in the world economy.

Pfaffenbach was asked if the G8 planned to expand its membership in the near future but he said that was not in the cards. "It is my impression that there is no consensus on expanding the G8," he said.

However, he said the G8 wanted to include countries like China, India, South Africa, Brazil and Mexico in negotiations and would be inviting them to the summit as part of the G8's so-called outreach programme.

He said they were among the key developing nations playing an increasingly important role in the global economy.