Finland is set to appoint the world's youngest serving prime minister, breaking records and stereotypes for women and young people in politics.

Key points: Sanna Marin will become Finnish prime minister after the Social Democrats voted her into the party's leadership

Sanna Marin will become Finnish prime minister after the Social Democrats voted her into the party's leadership The majority of party leaders in Finland are now women

The majority of party leaders in Finland are now women Marin ascends at a time when strikes threaten to halt production at major Finnish companies

Transport and Communications Minister Sanna Marin, 34, was chosen by her party, the Social Democrats, as leader after the resignation of current Prime Minister Antti Rinne.

Already dubbed "Finland's answer to Jacinda Ardern", she is set to take office in coming days, securing her title as Finland's third female government leader, its youngest-ever prime minister, and the youngest serving world leader.

The Social Democrats are the largest party in a five-member governing coalition. All of the parties now have women in leadership positions.

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Who is Sanna Marin?

Born in Helsinki, Ms Marin had a swift rise in Finnish politics, becoming head of the city council in the industrial town of Tampere at the age of 27.

She was raised by same-sex parents and told a Finnish magazine how her experience influenced her political career.

"It is only now in the 21st century that the debate on rainbow families has begun quite openly," Ms Marin told Menaiset.

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"We were not recognized as a true family or equal with others.

"For me, people have always been equal. It's not a matter of opinion. That's the foundation of everything."

Ms Marin gave birth to her daughter Emma Amalia last year and described her maternity leave from parliament as the happiest time of her life.

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She was appointed Minister of Transport and Communications in June this year and has been the Social Democratic Party's vice chairwoman since 2015.

She will become the youngest serving state leader in the world, followed by Ukraine's Oleksiy Honcharuk, 35; North Korea's Kim Jong-un, 36; president of El Salvador Nayib Bukele, 38; and New Zealand's Jacinda Ardern, 39.

Who else is leading Finland?

Ms Marin's appointment means that all five of Finland's coalition parties are led by women.

Centre Party chair Katri Kulmuni has been a Member of Parliament since 2015 and is the Minister for Economic Affairs.

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Li Andersson, leader of the Left Alliance and Minister of Education, has also been an MP since 2015.



Swedish People's Party of Finland leader Anna-Maja Henriksson has been in Parliament for over a decade and is in her third stint as Minister of Justice.

Green League chair Maria Ohisalo was elected as an MP earlier this year.

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Ms Marin's four fellow coalition party leaders all took to social media to congratulate the incoming prime minister on her success.

"Great congratulations to the Finnish prime minister @MarinSanna! It will soon be possible to continue our cooperation for a fair and lasting future," Ms Andersson tweeted.

With an average age of 37.4, the cohort of female leaders is almost a decade younger than the average age of all MPs who were elected in Finland's parliamentary elections earlier this year — 46.6.

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The average age of a member of parliament in Australia at the last election was 51.

Australia has had two prime ministers take office under the age of 40 — Chris Watson in 1904 and Stanley Bruce in 1923.

How is the world reacting?

Supporters and critics around the globe took to social media to voice their views on Ms Marin's appointment.

Many of the messages congratulated the new leader and praised the Social Democratic Party for its choice.

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But some supporters were driven to call out social media users who commented exclusively on Ms Marin's appearance.

A number of social media comments were screenshotted and reposted calling Ms Marin "cute" or "hot", even speculating that she would "smell nice".

Users also labelled her a "ridiculously photogenic prime minister", "sexiest head of state" and "absolutely stunning", with one joking she "should be PM of Fineland".

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"It is absurd to me that an extraordinary young woman can be so accomplished and yet people still voice their approval of her appearance as their first thought. Do better," Facebook user Nona Renee Raybern commented.

What sparked the change in government?

Mr Rinne resigned last week after the Centre Party said it had lost confidence in him over his handling of a postal strike.

Having emerged as Finland's largest party at an election earlier this year, the Social Democrats had the power to appoint one of their own as prime minister of the Nordic nation of 5.5 million people.

The ruling Social Democratic Party council voted 32-29 late Sunday to name Ms Marin to take over the government's top post, over rival Antti Lindtman.

Outgoing PM Antti Rinne may become the Social Democratic Party's vice-speaker. ( Reuters: Vesa Moilanen/Lehtikuva )

The new government will still have a comfortable majority of 117 seats at the 200-seat Eduskunta, or Parliament.

Ms Marin will take over in the middle of a three-day wave of strikes in Finland, which are expected to halt production at some of the country's largest companies this week.

"We have a lot of work ahead to rebuild trust," Ms Marin told reporters after winning a narrow vote for the party's leadership.

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Finland also currently holds the European Union's rotating presidency until the end of the year.

The appointment of Ms Marin and her new government will likely be approved quickly so she can represent Finland at the EU leaders' summit in Brussels, which begins on December 12.

ABC/AP/REUTERS