Saudi Arabia has given Iranian diplomats two days to leave the country, amid a row over the Saudi execution of a top Shia Muslim cleric, the BBC reports.
The Saudi government announced on Sunday that it had broken off diplomatic ties with Iran.
Iran has accused Saudi Arabia of stoking tension in the region.
Saudi Arabia and Iran are the major Sunni and Shia powers in the region respectively and back opposing sides in the conflicts in Syria and Yemen.
The US has appealed for calm, calling for continued diplomatic engagement.
Sheikh Nimr al-Nimr and 46 others were executed on Saturday after being convicted of terror-related offences.