Students in Athens protest police operation in northern Greece

Downtown Athens was briefly closed to traffic again on Monday evening, as students protested a police operation to end a sit-in at Aristotle University's School of Law in Komotini, northern Greece.

Protesters gathered at Athens University's historic Propylaea, burned flares and held up banners decrying the police's intervention at so-called university "occupations," usually involving a few dozen students barricading themselves into a school or faculty for several days.

Claims have emerged that the police used unnecessary force in the Komotini operation on Monday, throwing students to the ground and hitting them. Eighteen students were remanded, with six being released later in the day.

Sit-in protests and public rallies have gained momentum in recent days, ahead of planned legislation permitting private universities to operate in Greece.

Supporters of...