Nicolas Sarkozy, the French president, has warned China that the EU could penalise cheap imports from high carbon-emitting countries in order to defend European companies that are obliged to meet strict environmental standards.

In a speech to students at Beijing’s Tsinghua University, Mr Sarkozy urged China to shoulder its environmental responsibilities as a global economic power with some experts already saying it is the world’s biggest emitter of carbon dioxide.

But he said the EU, which regards itself as the world’s pace-setter in fighting climate change, would not indefinitely let its companies bear the brunt of this campaign if countries that mass-produce cheaper goods delay adopting similar standards.

“I will defend the principle of a carbon compensation mechanism at the EU’s borders with regard to countries that don’t put in place rules for reducing greenhouse gas emissions,” Mr Sarkozy said.