Seven migrants have been arrested after a homeless man was set alight in a Berlin subway on Christmas Eve, according to reports. Local press said the suspects, aged between 15 and 21-years-old handed themselves in to police after CCTV footage of the attack emerged.

In the footage a group of young men are shown boarding a U-Bahn train at Berlin's Schönleinstraße station, laughing. The police believe the group had earlier set fire to the clothing of a homeless man sleeping in the station.

German newspaper Bild reported that all seven of the suspects were refugees, six of whom were Syrian and one from Libya. According to the newspaper, two of the seven had resident status while the other five were seeking asylum, and that all seven had travelled to Germany between 2014 and 2016.

Local reports said police confirmed on Tuesday (27 December) that six men had handed themselves into police stations and a seventh had been detained by plainclothes officers. The prime suspect was said to be aged 21.

Despite the attack, the victim, 37, was unharmed thanks to the intervention of witnesses. Nonetheless, reports claimed an attempted murder investigation had been launched.

The suspects' status as migrants will likely fuel criticism of German Chancellor Angela Merkel's 'open-door' policy to migrants, amid the ongoing migrant crisis in Europe. Right-wing groups such as opposition political party Alternative for Germany (AfD) have been outspoken on the issue as Germany has experienced a wave of terror attacks this year, including an incident on 19 December when a truck ploughed into a busy Christmas market in Berlin.

Twelve people died and 49 were injured in the attack which was attributed to Tunisian Anis Amri, who had apparently been known to German authorities prior to the attack. Amri was shot dead in Milan days after the attack after he opened fire on police, who stopped him on a routine patrol.

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(L-R) Mayor of Berlin, Michael Muller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and Interior Senator, Andreas Geisel lay flowers near the crime scene where a lorry ploughed through a Christmas market on 20 December 2016 in Berlin, Germany Sean Gallup/Getty Images