Only the Iranian flag was flying at a reception in which Syrian President Bashar Al-Assad was meeting Supreme Leader of Iran Ali Khamenei President Hassan Rouhani in Tehran, causing controversy.
Activists said this indicates Tehran's "disrespect" of Al-Assad, despite their alliance, and their mutual interests.
However, others said that protocol dictated that the guest's flag be absent, this was refuted by some who said during other official visits foreign flags have been on display.
Activists posted photos showing the presence of the Iranian flag alone, during meetings with presidents, including Russian President Vladimir Putin.
A journalist with an interest in Iranian affairs added: "To my knowledge, the Iranian protocol does not stipulate the absence of the flag of the guest's country during the meetings with presidents."
"It is likely that Rouhani himself did not know about Al-Assad's visit until after his arrival, and the secrecy surrounding the visit did not allow bringing a Syrian flag and taking protocol into account."
Russia Today (RT) has previously quoted unnamed sources as saying that Khamenei's meetings with all world leaders and presidents are held at his home. He does not have a separate office and the universal protocol is not taken into account as he is the leader of the Islamic Revolution and not a government official or a president.