The European Union's climate change chief has advised Japan to be careful about exporting coal-fired power plants because the technology could prove "unsustainable" in light of the need to rein in global warming.

In a written interview ahead of a U.N. climate summit in Paris, EU Climate Commissioner Miguel Arias Canete said building coal-fired power plants "could lock countries into unsustainable technology: what is perceived as cheaper now could end up being expensive in the future."

Japan is seeing mounting pressure from Europe and the United States against its efforts to export coal-burning power plants. Japan is reputed to be the world's largest provider of public financing for coal-related projects overseas.