The European Union may limit United Nations credits tied to investments seen as subsidising rivals in the steel and cement industries, a trader at RWE AG said.

The EU, which runs the world’s biggest cap-and-trade program, has said it may ban industrial-gas offsets from the UN system. It may extend that ban to steel and cement factories in developing-nations because they compete with EU-based companies, said Bjorn Struck, senior emissions manager at the Geneva-based trading unit of RWE, Germany’s second-biggest utility.

“By buying Certified Emission Reductions, you are actually subsidising industry,” Struck told the Climate Finance 2010 conference today in London. “I expect those will be next,” he said, referring to steel and cement.

Proposed restrictions on UN credits linked to industrial gases probably wouldn’t undermine the market because it’s oversupplied, Struck said.

“There will be enough Certified Emission Reductions available for meeting the absorption capacity of the EU emissions trading system,” he said. “I don’t think the restrictions will affect the EU ETS a lot.”