The Greek police said that it arrested more than 600 people in central Athens last week.
In a statement, the force said that more than 15,000 people and almost 800 vehicles were checked between June 2 and June 8. A total of 6,423 people, almost 5,500 of whom were foreign nationals, were detained.
The arrests were made mostly for robberies, drugs offenses and failure to produce valid residence permits.
The police said that it also made checks with municipal police on illegal street traders, leading to the seizure of almost 6,000 items of knock-off clothing and more than 2,500 CDs and DVDs.