A shocking video of a group of migrant men attacking two pensioners who allegedly stopped them from groping a young woman on the subway in Munich has sparked a police hunt.

The footage shows the gang of around five men - who appear to be of 'Arab' origin - roughly seizing one elderly man by the arms as they shout abuse at him.

The second elderly victim can be seen grappling with one of the gang, before he is held up by the neck and threatened.

Detectives in Germany have today launched a hunt for the gang, and are appealing for witnesses to come forward in the criminal investigation.

Munich man Tom Roth uploaded the footage - captured while travelling from Sendlinger Tor station to the Metro's city centre terminal - to his Facebook page.

He said the fight broke out after a female passenger rejected the advances of one of the gang, after he placed his hand on her back.

In response, the man smashed his hand against one of the carriage's glass windows - which caused outrage among the shocked passengers.

When one of the elderly men asked the group to stop being so aggressive and leave the woman alone, one patted him mockingly on the head.

That act of disrespect sparked a furious exchange.

Translated, the post accompanying Mr Roth's video upload reads: 'A young woman was attacked on the subway. When two old men tried to intervene, they too were attacked.

'This was in the heart of Munich, in the middle of the day. I got on the train at Sendlinger Tor travelling to the main railway station. I sat in a four-seater, across from a young lady.

'In the four-way behind her sat two asylum seekers. One of them, a young man, probably of Arab origin, bothered the woman.

Recorded on a mobile phone, the disgraceful video shows the men - of Eastern European or Arabic origin - holding one man by the arms as they verbally abuse him. The second victim is seen grappling with one of the migrants, before he is held up by the neck and threatened (pictured)

Munich man Tom Roth uploaded the disgraceful video to his Facebook page. He caught the footage while travelling from Sendlinger Tor station to the Metro's city centre terminal. He said the fight broke out after one of the asylum seekers was rejected by a woman who he had placed his hand upon on the train

'He said something to her and asked: "Why will you not answer me in German?"

'She responded: "Because you asked me in English". I think he had his hand on her back. She turned away and looked in my direction.

'As the train continued, the asylum seeker struck the glass window full force. I guess he was angry the woman rejected him. Several gentlemen shouted at him to stop.

'One of these men, in the four seats beside me, was then touched on the head by one of the asylum seekers wearing a brown jacket. He stroked his bald head, to mock him. It was such disrespectful behaviour, the likes of which I have rarely seen before.

'The gentleman stood up right away. The asylum seeker then turned, approached the man and grabbed him by the neck. Everyone immediately became involved, with many trying to get in between the pair.

Mr Roth claimed one asylum seeker smashed his hand against the carriage's glass window - an aggressive act of defiance the train's other passengers requested he desist. When they did, one elderly German man was patted mockingly on the head by one of the migrant group. That act of disrespect sparked an angry exchange

'The man's attacker fell back in his four-seater. There were four asylum seekers now involved, staring at us and two other older gentlemen angrily.

'There were about 10-15 people beside and behind me. The situation was brought under control. When the train reached the station I shouted that I would call the police.

'Some of the other passengers yelled that they should leave the train, which they then did. I didn't call the police after all, since I have been told several times by friends that the police tell victims there's nothing they can do about it.'

Police have today launched an investigation into the video, after finding it on 'a social network', which is reportedly focused on the man in the brown/orange jacket.

'We know about the video, after we found out about it on a social network,' a spokesman for Munich police department told MailOnline.

‘Based on the video and the witness account we have decided to open a criminal investigation. We are in contact with a witness, but still need to identify the other people in the video.

‘For starters, we need to find out whether any actual bodily harm and/or sexual harassment can be established.

‘It would appear from the video that the aggressors have Arab backgrounds, but whether they are asylum seekers or not we can’t say at the moment.

‘It’s mere speculation. We are working to identify them.’

The incident is the latest violent coming together of asylum seekers and Germans to have come to light in recent weeks. Migrants are seen arriving by train at Munich Hauptbahnhof railway station on September 12 last year

It follows New Year riots in Cologne triggered by a number of sexual assaults made against local women by a group of up to a 1,000 men 'of Arab and North African origin'

He added: ‘People should always call the police in such situations. We act straight away and will be there in a matter of minutes if something occurs in the subway. The public transportation in Munich is generally very safe.

‘Things occur from time to time, but this is the first case of this sort I am aware of.’

The incident is the latest violent coming together of asylum seekers and Germans to have come to light in recent weeks.

It follows New Year riots in Cologne triggered by a number of sexual assaults made against local women by a group of up to a 1,000 men 'of Arab and North African origin'.

Police described the series of assaults against women outside the city's main train terminal as 'a completely new dimension of crime'.

Mr Roth stressed that after his own experience, he believes German chancellor Angela Merkel must now take action to protect the country's citizens.

He said: 'I just felt the need to share this. Those involved were very distressed. An older lady said she doesn't leave her home at night any more. The two gentlemen said that it cannot go on like this.

'I felt safer in Germany two or three years ago. I find that terrifying and sad.