The 11-party alliance began a sit-in in Dhaka on 6 August to protest fuel and gas shortages, "ghost" electricity bills, a decline in law and order, and rising prices of essential goods.
All gates of the Bangladesh Secretariat were closed at midday on Thursday, and extra police were deployed in front of them.
A march moving toward the Secretariat was stopped by a police barricade at the Zero Point area.
Members of the public who came to the Secretariat for official work found the gates shut and waited outside.
The sit-in started after 11 a.m. at Muktangan, and participants continued despite rain that began around 11:50 a.m.
Participants included Nahid Islam, convener of the Anti-Discrimination Students' Movement, Jamaat-e-Islami amir Dr Shafiqur Rahman, and Liberal Democratic Party president retired Colonel Oli Ahmad.
Other alliance leaders present included former lawmakers Mia Golam Parwar and Dr Hamidur Rahman Azad, and JAGPA spokesman Engineer Rashid Pradhan.