Saudi Arabia says it has broken off diplomatic ties with Iran, amid a row over the Saudi execution of a prominent Shia Muslim cleric.
Saudi Foreign Minister Adel al-Jubeir was speaking after demonstrators had stormed the Saudi embassy in Tehran.
Sheikh Nimr al-Nimr and 46 others were executed on Saturday after being convicted of terror-related offences.
Mr Jubeir said that all Iranian diplomats must leave Saudi Arabia within 48 hours.
Saudi Arabia was recalling its diplomats from Tehran, he said.
Mr Jubeir said Saudi Arabia would not let Iran undermine its security, accusing it of having "distributed weapons and planted terrorist cells in the region".
"Iran's history is full of negative interference and hostility in Arab issues, and it is always accompanied by destruction," he told a news conference.
US state department spokesman John Kirby said: "We will continue to urge leaders across the region to take affirmative steps to calm tensions".
"We believe that diplomatic engagement and direct conversations remain essential," he said.
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