FINLAND formally announced its decision to join the US-led Nato military alliance today, with Sweden expected to follow suit imminently.

Finnish President Sauli Niinisto and Prime Minister Sanna Marin made the announcement at the presidential palace.

Russian President Vladimir Putin — whose invasion of neighbouring Ukraine has prompted Finland and Sweden to seek Nato membership — tried to dissuade Mr Niinisto on Saturday, warning it would be a “grave error” and might prompt Russia to deploy nuclear warheads in its western exclave of Kaliningrad.

And Finland and Sweden’s accession could be slowed by Turkey, whose President Recep Tayyip Erdogan said on Saturday that their bids were “unacceptable and outrageous” because of what he said was their support for Kurdish nationalist groups. He said Turkey would not repeat the mistake it had made in allowing Greece to join.

Every Nato member can veto new accessions, but Nato deputy secretary-general Mircea Geoana suggested today that he believed Turkish objections could be smoothed over. 

Turkey may press Sweden and Finland to crack down on Kurdish organisations in return for membership. Finland would add over 800 miles of direct Nato-Russia border, likely accelerating the military build-up in eastern Europe.

Russian Deputy Foreign Minister Alexander Grushko said Finnish and Swedish accession would force the militarisation of the Arctic.

Fighting in Ukraine continued over the weekend, with Ukrainian officials saying that Russian troops were pulling back from the country’s second-biggest city Kharkiv.

But the assault on Ukrainian-held areas of the Donbass continued, with mortar, artillery and air strikes against Ukrainian positions.

Both Russian and Ukrainian troops claimed to have taken or liberated various Donbass towns as the front line shifts. 

Ukrainian President Volodymyr Zelensky said that his armies were “forcing the occupiers to leave Ukrainian land step by step” and vowed after the country’s Eurovision song contest win on Saturday night that it would host a future contest in Mariupol, the Black Sea port currently occupied by Russian troops.

G7 leaders meeting in Germany called on Russia to allow the export of Ukrainian grain from Black Sea ports, warning that Mr Putin would be responsible for global food shortages otherwise.

But the Russian Foreign Ministry said soaring food prices were the result of Western sanctions on its own grain exports and declined to comply.