Green Exchange LLC, an emissions market owned by CME Group Inc.’s New York Mercantile Exchange, may offer a United Nations offset contract starting next month.

The emissions contract would “ensure that buyers get what they need for compliance purposes,” Henrik Hasselknippe, a London-based managing director at the exchange, said today by phone. Green Exchange is asking clients what they need, he said.

The UN’s Certified Emission Reductions can be used by emitters in the European Union’s cap-and-trade program, the world’s largest, as a less-expensive alternative for compliance with their pollution limits. So-called CERs are created along with projects to curb emissions in developing nations. The EU has proposed restricting credits from certain projects starting in 2013.

Green Exchange’s CER contract is “written very specifically to cover EU eligibility,” when phase three of the trading system begins in 2013, Hasselknippe said. “To create something that is flexible enough to deal with any regulatory outcome.”

ICE Futures Europe, the exchange with the biggest share of the carbon market, proposed last month that offsets used for settlement against its contracts must comply with European trading rules.