An Afghan who stabbed a refugee aid worker to death in Germany has walked free from court after judges ruled he had acted in self-defence.

The 18-year-old defendant, named as Seyed M., was accused of manslaughter after 20-year-old Jose M. died in a park in Ochtrup, north-west Germany, last May in a row about a girl.

Prosecutors at the court in Münster had demanded a three-year jail sentence but judges ruled Seyed had been defending himself, Bild reported.

The court heard Jose had put the Afghan in a headlock and punched him in the face, and that Seyed had initially tried to defend himself more 'mildly' with a glass bottle.

Accused: Seyed M. allegedly stabbed Jose M. six times with a 5.5-inch bread knife but judges ruled he had been acting in self-defence after the aid worker punched him

The row was said to have erupted last year after refugee worker Jose told Seyed to stop harassing a female friend.

The prosecution claimed Seyed M had 'fallen in love' with a girl, but that she had rejected him.

The two confronted each other in a park in the early hours of May 22, with Seyed allegedly bringing a 5.5-inch bread knife.

Stabbed: Jose M. was killed in May last year in what was allegedly a row over a girl

He was accused of hitting Jose on the head with a beer bottle and then stabbing him six times, piercing his heart and fatally wounding him.

But the court heard Jose had first punched the Afghan in the face, and judges concluded Seyed had acted in self-defence.

Judges said Jose had put the younger man in a 'headlock' and that Seyed had initially used the glass bottle as a 'milder' way to resist the attack.

There were 'six boxing classes' between them and Seyed was physically weaker, the judge said.

The verdict might be 'incomprehensible' to the victim's family but courts had to make 'neutral and emotionless' decisions, he said.

The prosecution had argued that six stabs of the knife were more than was needed for Seyed to defend himself.

According to RTL the Afghan, who came to Germany three years ago, had also faced deportation if he was convicted.

Earlier in the case the victim's tearful mother had appeared in court and faced her son's alleged killer.

She described Jose as a committed young man and said he was 'there whenever someone needed help'.

'It didn't matter if they were black or white, red or green, German or not German - he'd be there', she said.

Jose had wanted to become a teacher and was a member of the town's youth parliament, she said.