German utility RWE (RWEG.DE: Quote, Profile, Research) said on Wednesday it will raise its prices for gas for 600,000 customers in September and October by up to 27 percent because of climbing energy prices.

A spokesman for the utility's subsidiary RWE Energy said the price rise will take place between Sept. 1 and Oct. 1. It will cost the average German household some 26 to 29 euros more per month.

Some German regional subsidiaries of rival E.ON (EONG.DE: Quote, Profile, Research) are also preparing to raise gas prices by up to 15 percent as of August on the same grounds.

Natural gas, used by over 40 percent of German households for heating, is index-linked in continental Europe to the price of crude via long-term contracts with producers such as Russia and Norway.

Germany imports 80 percent on its natural gas.