Government House and surrounding areas within a 50 metres radius are expected to be declared a "controlled zone", where any public gatherings are prohibited, said a deputy national police chief Sunday.

Anti-regime activists have vowed not to let barriers erected by security forces prevent them marching on Government House Tuesday.

Police blocked the Na Phra Lan Road in front of Thammasat University late on Tuesday morning to prevent anti-military regime demonstrators leaving for a march to Government House.

Police are threatening tough legal action against hardcore elements of red-shirt groups if they attempt to instigate unrest on the fourth anniversary of the 2014 coup on Tuesday.

Anti-government protesters demanding elections by November prevented from marching to Government House.

Activists and supporters for an election will continue their planned march from Thammasat University to Government House on Tuesday.