A man set fire to another man in a street near Brighton Station.
The victim, who lives in Portslade, has poor vision and walks with a cane.
Sussex Police said that the attack happened in Guildford Road, Brighton, at about 4.45pm on Friday (17 May).
The attacker taunted the 38-year-old victim before setting his jumper alight.
The suspect was described as a slim white man aged in his sixties, between 5ft 8in and 5ft 10in tall, and with light coloured or grey hair.
He was wearing pale coloured clothing which included an open jacket.
Detective Constable Darran Newman said: “This is a shocking attack on a vulnerable member of our community.
“Thankfully he was not injured but could have been badly burnt if he was not able to extinguish the flames himself.
“We need anyone with information about the person responsible or anyone who may have witnessed the incident to come forward immediately.”
Anyone with information is asked to call Sussex Police on 101 or the independent charity Crimestoppers anonymously on 0800 555111.
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