TEHRAN (Press Shia) – Britain’s Ambassador to Tehran Nicholas Hopton said he was “deeply saddened” after a number of people affiliated with an extremist religious group stormed Iran’s embassy in London.

“Deeply saddened by what happened at Iran’s Embassy in London on Friday,” Hopton tweeted in Persian on Sunday.

London honors the Vienna Convention, he further stressed, adding that “security and safety of diplomats and diplomatic missions” in the UK are of primary importance.

The 1961 Vienna Convention on Diplomatic Relations defines the privileges of a diplomatic mission that enables diplomats to perform their function without fear of coercion or harassment by the host country.

In the attack on Friday, four men dressed in black climbed on to a first-floor balcony of the building, took down the Iranian flag, and waved flags of their radical cult in an apparent protest against the Islamic Republic.

No one was hurt during the incident and the trespassers were arrested when they came down after around three hours. The four were detained for causing criminal damage and being unlawfully on diplomatic premises, a spokeswoman for London’s Metropolitan Police said.

Immediately after the incident was reported, Iran’s deputy foreign minister for political affairs, Abbas Araqchi, expressed the Islamic Republic of Iran’s strong protest to the British ambassador to Tehran and demanded that the UK police fully protect Iranian diplomats in London and immediately deal with the assailants.

Also, Iran’s ambassador to Britain, Hamid Baeidnejad, tweeted that the assailants were “advocates of the Shirazi cult”.