He told reporters that a cultural institute had installed unauthorized billboards without knowledge of Tehran municipality bearing anti-US slogans.
He made it clear that all the public enterprises are required to get prior approval of Tehran Municipality cultural council for the billboards.
On the eve of 13 Aban (November 4), anti-US posters were pasted on billboards at various parts of Tehran.
On November 4 security officers of Pahlavi regime killed several students who staged anti-Shah demonstrations in 1978 which was declared the -- students day -- and the -- anti-US day -- because of the US unconditional support for Pahlavi regime and involvement in military takeover in 1953 which toppled the legitimate government of prime minister Mohammad Mossadeq.
Washington has admitted involvement in the military takeover and yet to apologize.