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, data from the Mallnow metering point on the German-Polish border showed. Once again, additional capacity was booked in the reverse direction from Germany to Poland at a day-ahead auction, analysts at Refinitiv said. The long run of reverse flow has sparked concerns about winter gas supply in Europe, higher prices and political tension with Russia, which has repeatedly said it is meeting all its contractual obligations. read more The pipeline accounts for about one sixth of Russia"s normal annual gas exports to Europe and Turkey. read more The front-month gas contract on the Dutch TTF hub - a European benchmark - traded above 100 euros on Friday for the first time since Dec. 29. It traded up 5 euros at 103 euros per megawatt hour (MWh) by 0740 GMT. Capacity nominations for Russian gas flows from Ukraine to Slovakia via the Velke Kapusany border point, another major route for Russian gas to Europe, also eased on Friday and remain at low levels overall. Nominations stood at 290,259 megawatt hours (MWh) per day, a touch below Thursday"s levels and well below levels of over 900,000 seen in early December, data from Slovak pipeline operator Eustream showed.