Tayman Bahmani, 30, died in hospital from a single stab wound in what police are treating as a racially motivated attack.

An 18-year-old man was arrested in Edinburgh early on Friday and was being brought back to the Northumbria Police force area for questioning.

Three other people, two men and a woman, are continuing to be questioned in connection with the fatal stabbing, which happened in the Hendon area of the city.

Street confrontation

Officers have been granted an extended licence to hold them in custody which will last until Saturday lunchtime.

Mr Bahmani fled to Britain from his native Iran two years ago.

He died after a confrontation between two groups, one white and the other Iranian.

He later died in Sunderland Royal Infirmary from his injuries.

Police have yet to officially name the dead man, but an ethnic rights organisation, The Monitoring Group, released his name on Thursday.

Additional forensic experts are being brought in from London to help with the inquiry.

Police on Wearside have asked local people to remain calm after the death.