The search focused on the makeshift camps set up by the migrants arriving in Patras, where many live in appalling conditions as they wait for an opportunity to travel to Italy or other countries in central and northern Europe.
Police detained a total of 49 foreign nationals, arresting 47 because they did not possess legal documents for entering and staying in Greece. The migrants arrested will stay in custody until deportation procedures are completed.
This is the third such operation by Patras police in the last few days. The two previous searches were conducted in the railway depot at Agios Andreas near the port, where dozens of migrants were caught.
After the operations were complete, the Greek Railway Organisation (OSE) removed the old, empty carriages that migrants had been using as shelters.