OSLO, Jan 7 (Reuters) - The Yamal-Europe pipeline, which usually sends Russian gas west into Europe, was flowing east from Germany to Poland on Friday for an 18th successive day, albeit at marginally lower levels than on Thursday, data from German network operator Gascade showed.

Eastbound volumes stood at 6.7 million kilowatt hours an hour (kWh/h), down from 7.5 million on Thursday evening, data from the Mallnow metering point on the German-Polish border showed.

The pipeline accounts for about one sixth of Russia's normal annual gas exports to Europe and Turkey.

European gas prices have risen on Yamal's reverse flow, which has sparked concerns about winter supply in Europe, and due to political tensions.

(Reporting by Nora Buli in Oslo; Editing by Susan Fenton)