The Renewable Fuels Association want environmental officials and federal regulators to investigate possible manipulation in the market for U.S. biofuel credits. RFA President and CEO Bob Dinneen says they want to know what’s happening given the recent volatility and surge in prices that are not related to the marketplace.

Renewable Identification numbers or RINS have climbed about 30 percent since mid-May. And last week RINS approached three year highs as traders raced to buy the credits. Dinneen says his group is concerned there’s political motivation behind the hike in biofuel credits.

He says both the EPA and Commodity Futures Trading Commission need to follow through with their earlier agreement to work together to probe into the matter.

Dinneen says the CFTC and the EPA need to determine whether certain parties may be exerting undue influence on prices or otherwise engaging in manipulative practices.