Islamic State has released a video showing an Afghan asylum seeker apparently making threats with a knife, before carrying out an axe attack on a packed German train.

The 17-year-old refugee injured five people before being shot dead by police.

In the video, he refers to himself as "an I.S. soldier".

It is understood that he sent the video to Islamic State.

However, German public prosecutor Erik Ohlenschlager doesn't think the teenager had direct links to the group: