Athens: Greek police have arrested a "key suspect" in the murder last year of Greek-Australian gangster John Macris in Athens, the Sydney Morning Herald and The Age understand.

A police source said the suspect was a Turkish-born Bulgarian, who had hidden in an Athens safe house for the five months since the attack.

Macris, a Sydney businessman with links to organised crime, was shot dead in his car outside his home in an Athens seaside suburb on October 31.

Police had been investigating whether Macris had any potential Athens underworld connections. He had set up a security business in the Greek capital and was on the way to its official launch when he was killed.

According to Greek media reports, the 31 year-old Bulgarian was arrested along with an accomplice.

More to come