Seven men have been arrested in Finland accused of repeatedly raping a ten-year-old girl in a grooming case that has shocked the Scandinavian country.

The girl has allegedly been subjected to multiple sexual assaults over several months in the suspects' homes in Oulu in northern Finland, police say.

The men, aged 20 to 40, have all arrived in Finland as migrants or refugees in recent years, and are thought to have made contact with the victim on social media, local media reports.

Shocking: The ten-year-old victim has allegedly been subjected to multiple sexual assaults over several months in the seven suspects' homes

'For young people, meeting a foreign-heritage man [a person whose parents are not Finnish or who themselves are not Finnish] can happen spontaneously, for example during a party,' criminal investigator Markus Kiiskinen of Oulu Police told Ilta-Sanomat.

'Someone could offer them something "nice", like tobacco or alcohol, which can start a nasty chain of events. '

Kiiskinen said that the suspects all knew each other, and that the young victim is not related to any of the alleged rapists.

The case has prompted the Oulu Police to issue a warning to the public about 'foreign men' contacting underaged girls on social media.

'The police is urging young girls and parents to be vigilant on social media. Recently, in the Oulu region, there have been incidents where foreign-born, often non-Finnish men have contacted minors online.

'At worst, there contacts have led to serious sexual offenses,' the statement reads adding that parents need to be aware of whom their children spend time with both on- and offline.

Warning: The incident has prompted police in Oulu to issue a warning to parents to monitor who their child speaks to on social media

Anger: Prime Minister Juha Sipilä expressed his shock and anger in a tweet

Finland's Prime Minister Juha Sipilä took to Twitter to express his shock and anger, writing that 'A sexual offence against a child is an inhumane act, and its wickedness cannot be comprehended.'

President Sauli Niinistö branded the crimes an 'evil' which must be fought in an interview with a Finnish newspaper.

Oulu is a harbour city in north-west Finland, home to some 202,000 people. Of Finland's population of just over 5.5million, some 321,500 people are born in a foreign country.

Compared to neighbouring Sweden, Finland had a low intake of migrants and refugees during the recent European migrant crisis.

Last year, 31,797 persons moved to Finland, down from 34,905 in 2016 and 28 746 in 2015.