Helsinki, 5 April 2023 (dpa/MIA) - Finland's former prime minister Sanna Marin has said she will resign as leader of the Social Democrats following her party's defeat in parliamentary elections on Sunday.

She will not stand for re-election as party leader at a party congress in September, the 37-year-old said in Helsinki on Wednesday - one day after Finland's official accession to NATO.

The last few years had been difficult, but now she had the opportunity to step aside, Marin said. She would nevertheless lead the negotiations on her party's potential participation in the new government.

She had not been offered an international post, she said, in response to speculation that she might seek a position abroad in Europe after the election defeat. She was also not available as a candidate for the Finnish presidential election in early 2024, when a successor to Sauli Niinistö will be elected.

Marin's Social Democrats were only the third strongest force in the election behind the conservative National Coalition Party and the right-wing populist party The Finns. This means that a change of government is imminent in Helsinki.

The conservative election winner Petteri Orpo wants to hold talks with all parties after Easter about a possible new governing coalition.

Marin has been prime minister since the end of 2019, leading a centre-left coalition consisting of five parties. On Thursday, she will formally submit the resignation of her government, Marin said.

Until a new government has been formed, however, she will remain in office on an acting basis. After that, Marin wants to continue as a normal member of parliament.