Norway remained Western Europe's top gas supplier in 2015, but Russia narrowed the gap from the previous year, preliminary data showed on Jan. 4.

Russia is the top supplier for the whole European Union - supplying around a third of its gas - when countries in Eastern Europe are included.

Norwegian pipeline gas exports to Europe surged to a record 108.6 billion cubic metres (bcm) in 2015, up from 101.1 bcm in 2014, preliminary data from gas system operator Gassco showed.

Russia's pipeline gas monopoly exporter Gazprom sent to Western Europe 104 billion cubic metres of gas, up from 95 bcm in 2014, data from Thomson Reuters Point Carbon showed.

Russia's gas export pipelines have become intensely political because of the conflict in Ukraine, the traditional transit route for shipping Russian gas to the EU. But the desire for secure supplies of cheap gas has offset some EU nations' demands to seek alternative sources.

"Norway pipeline gas exports to Western Europe exceeded Russian supplies last year, but the gap narrowed from the previous year as Russian gas prices fell to near the levels at the European gas trading hubs," said Marina Tsygankova, an Oslo-based analyst at Thomson Reuters Point Carbon.

The data include Czech Republic and Slovakia, but exclude other EU member states in Eastern Europe, as well as the Baltic states. They broadly cover the same countries Norway exports to.

"It's interesting that supply from both Norway and Russia increased in 2015, partly because of output reduction from the Dutch Groningen field," Tsygankova said.

Norway's exports rose last year also due to increased production from the country's biggest field, Troll, she added.

Troll is operated by Norway's Statoil, which markets about 70 percent of the Nordic country's gas.

By the end of 2015, Brent crude had shed two-thirds of its value since mid-2014, but jumped on Monday on tensions between Iran and Saudi Arabia, the world's biggest oil exporter.

Russia sells gas to Europe mainly at oil-linked prices, while Norwegian exports are mainly indexed to spot prices at the European hubs.