Rolls of razor wire and barricades were placed around royal ground in Dusit and Phra Nakhon districts on Wednesday, blocking important places including the Crown Property Bureau and Government House.
The barricades were installed even though anti-government protesters announced they were moving their afternoon rally from the CPB to SCB Park, the headquarters of Siam Commercial Bank, in Chatuchak district.
Cargo containers were stacked on roads to Government House, Royal Plaza and the Crown Property Bureau.
Soldiers in plain clothes were seen around the CPB, which anti-government protesters had earlier announced as their target on Wednesday.
Makkawan Rangsan Bridge was closed to traffic, and also parts of Rajavithi, Samsen, Sawankhalok, Si Ayutthaya and Wisut Kasat roads.
Ongoing anti-government protests and the police responses have caused heavy traffic congestion in the capital.
Youth-led protesters have demanded the resignation of the prime minister, constitutional changes and the reform of the royal institution.
