Germany's environmental minister Juergen Trittin said RWE AG may be using rising prices in CO2 emissions certificate trading as a pretence to hike electricity prices, Financial Times Deutschland said, citing a letter Trittin sent to Germanys energy giant by the minister.

In the letter, Trittin demanded detailed information on RWE's emissions certificate trading operations, including how many certificates the company bought and sold this year and at what price.

Trittins demand comes after an association of industrial energy consumers (VIK) lodged a complaint against RWE and three other German power companies for using emissions certificate trading as a excuse to charge higher rates. Trittin sent similar letters to the other energy producers -- E.ON AG, Vattenfall Europe AG and Energie Baden-Wuerttemberg AG. It is in no way comprehensible that certificates that are received free of charge result in increased energy prices, read part of the letter sent to RWE.