Greenpeace activists scaled the headquarters of energy firm Fortum's headquarters in Espoo, Finland, on Wednesday, to hang a banner urging the state-owned company to end business links with Russia.

The firm's subsidiary, German-based Uniper, is one of the biggest importers of Russian gas to Europe.

Fortum, which is nearly 51 per cent owned by the Finnish state, is by far the country's largest energy company. It raised eyebrows last week by announcing that Uniper was preparing to use a new Kremlin-required purchase arrangement for fossil gas via a Russian bank, which has been criticised as circumventing EU sanctions.

Eight activists hung the colourful banner emblazoned with a peace symbol, the Greenpeace logo and the phrase: "Stop fuelling war!"