Some 200 migrants and asylum seekers blocked a side-road off the Athens-Lamia national highway in eastern Attica for several hours on Tuesday.
The migrants are residents of a camp in Malakassa, northeast of the Greek capital, and held a peaceful sitting protest on the road after reportedly failing to block traffic at a railway station in the area earlier in the day.
Another group of residents from the Malakassa camp had held a sit-in protest at the rail station on August 30.
The purpose of Tuesday's protest was not immediately clear, though some media suggested that the migrants are demanding permission to ride the train for free.
Their action prompted the closure of a section of the highway between Avlona and Malakassa, causing delays.