Prime Minister Sanna Marin (SDP) said the nations of Europe must stand together behind Ukraine as the country defends itself against Russia's "brutal war".

"We must continue our support of Ukraine. We have to be strong and we have to be united," Marin said.

Finland's PM was speaking at a press conference in Oslo on Monday, where she had travelled to meet with the prime ministers of Norway, Sweden, Denmark and Iceland at an informal summer gathering.

Marin further extended her message to countries around the world, saying Russia's invasion of Ukraine must remain a priority.

"Our message to all our partners and friends in Asia, in Africa and the Americas is that it is not OK to close our eyes to Russia's war," she said.

The main theme of the meeting was the development of Nordic defence cooperation as Finland and Sweden prepare to join Nato, of which the other Nordic countries are already members. The five Nordic prime ministers are also scheduled to have a joint meeting with Federal Chancellor of Germany Olaf Scholz as part of the programme.

Speaking at the press conference, Norwegian Prime Minister Jonas Gahr Støre described the meeting as "historic", in reference to Finland and Sweden's applications for Nato membership.

In response, Marin noted that the other Nordic nations were among the first to ratify Finland and Sweden's applications. Currently, 23 of the 30 Nato member countries have approved the two membership bids.

"I want to warmly thank Norway, Denmark and Iceland. You took the lead within Nato in the ratification of our membership," Marin said.

This past weekend saw French President Emmanuel Macron signing Finland's Nato membership protocol on Sunday, while on Saturday, Finnish President Sauli Niinistö released a video with US President Joe Biden and Swedish PM Magdalena Andersson, in which Biden confirmed the US's commitment to the security of the Nordic countries.