Seven Syrian migrants and a German citizen have been arrested for a four hour gang-rape of an 18-year-old girl in bushes outside a nightclub.

The Syrians between the ages of 19 and 29, along with a 25-year-old German, have been arrested in Freiburg in the south-western German state of Baden-Wuerttebmberg.

Officials said the ordeal took place in bushes outside the venue after one of the suspects sold the victim ecstasy and bought her a drink on October 14.

The main suspect allegedly set upon her outside the nightclub and then called on others to do the same.

Alleged chief suspect Majd H., 21, poses in his homeland with a large machine gun

The nightclub in Freiburg where the victim was sold drugs before being gang-raped nearby

Police are investigating whether the drink may have been spiked with an unknown substance.

Local newspaper Bild identified the main suspect as 21-year-old Syrian Majd H. and some of his accomplices have been named as 19-year-old Ahmed Al H., 24-year-old Muhammad Al H., and 20-year-old Muhanad M.

According to Bild, Majd H., who is pictured with a machine gun on his social media profile, came to Germany in 2014 and has already had one conviction in the European country that took him in.

They quoted his father as saying: 'Majd became more aggressive after we fled and he has been in trouble with the police. He already has one conviction because he hurt someone.'

According to local media, the other suspects lived mostly in asylum centres and were known to the police for other alleged criminal offences.

The horrific story will bolster Angela Merkel's critics, as support for her coalition has wavered in the face of the migrant crisis.

Angela Merkel meets with Greek prime minister Alexi Tsipras after previous Freiburg rape

The picturesque university town of Freiburg which has been ravaged by migrant crime

Merkel who has held the Chancellorship since 2005 is stepping down at the end of her term in 2021.

Her coalition faced collapse after permitting the inflow of nearly a million refugees and asylum seekers as part of her 'Willkommenskultur' - welcoming culture, in 2015.

A police spokeswoman told local media that they are still looking for other possible perpetrators after finding evidence at the crime scene indicating that more people took part.

Freiburg was already reeling from the rape and murder of 19-year-old Maria Ladenburger, the daughter of an EU official.

Afghan asylum seeker Hussein Khavari was jailed for life earlier this year after he raped the student who worked as a refugee helper.

Afghan asylum seeker Hussein Khavari was jailed for life earlier this year when he was 17

The teenager shakes hands with his lawyer as he is escorted through court in handcuffs

The asylum seeker was convicted of raping and killing 19-year-old Maria Ladenburger

In June this year, local daily 'Schwarzwalder Bode' reported that a series of migrant sex attacks have brought fear to the local population of 226,000.

The newspaper wrote: 'An unprecedented series of sex offences has shaken the public's sense of security.'

The paper was backed up by Freiburg police spokesman Dirk Klose, who said: 'To my knowledge, we have never had so many offences of this kind before.'