An unknown man suffered serious injuries and was in coma at the Patra hospital following a gang attack on Sunday night, according to local reports.
The victim, who is said to be an illegal immigrant, was assailed by a group of men on motorbikes. He was rescued by people who were watching a play at a nearby theater.
Witnesses have identified one of the assailants as a local member of the far right Golden Dawn party, according to a local newspaper.
Brutal attacks against migrants in Greece are becoming almost a daily occurrence, with violent mobs acting almost unhindered as police have failed to make any significant arrests.