The Galle Face entrance road was closed from Lotus Roundabout due to a protest march by the Frontline Socialist Party.
The protest demands the release of party member Kumar Gunaratnam, who was arrested over Immigration and Emigration law violations on November 4. He has been kept in remand custody after his arrest.
The protesters also demand Gunaratnam's political rights.
The protest was heading towards the Presidential Secretariat and police had brought in water cannon.