(CNN) Estonia's President has apologized after the country's interior minister mocked Finland's newly elected leader and described her as a "sales girl."

The leader of Estonia's populist far-right party EKRE, Mart Helme, questioned the ability of Finnish Prime Minister Sanna Marin , 34, to run her country on Sunday.

"Now we see how one sales girl has become a Prime Minister and how some other street activists and non-educated people have also joined the cabinet," Helme said on his party's radio talk show Sunday, according to Estonian public broadcaster ERR.

Marin -- who leads Finland's Social Democratic party -- has spoken about her life growing up in a disadvantaged family and working as a cashier, before she studied at university.

She became the world's youngest sitting Prime Minister earlier in December after replacing the nation's former leader, Antti Rinne. Five of Finland's major parties in parliament are all led by women, four of whom are in their 30s.

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