The Azerbaijan foreign ministry says four embassy employees engaged in activities “incompatible with diplomatic status.”
Azerbaijan said it would expel four Iranian diplomats for “provocative actions” in the latest deterioration in relations between neighboring countries.
The move on Thursday came hours after Baku said it had arrested six men, whom it claimed had links to Iran’s secret services and plotted a coup in the Caspian nation.
Relations between neighboring countries have long been tense, with Azerbaijan being a close ally of Iran’s historic rival, Turkey. Baku has also deepened relations with Iran’s regional rival Israel in recent years.
The foreign ministry in Baku said on Thursday it had “summoned” the Iranian ambassador, telling him that “four employees of the Iranian embassy had been declared persona non grata” with 48 hours to leave the country.
It said they engaged in activities “incompatible with diplomatic status” but did not provide further details.
Earlier in the day, Baku said it had arrested six Azerbaijani nationals, who it said were “recruited by the Iranian secret services to destabilize the situation in the country”.
It announced the arrests in a joint statement from the Ministry of the Interior, the State Security Service and the prosecutor’s office. There was no immediate comment from Tehran.
Azerbaijan closed its embassy in Tehran in January after its head of security was killed in an attack. It opened an embassy in Israel last week.
Iran has attacked Azerbaijan for moving closer to Israel, with the State Department saying it considers the burgeoning relationship between Azerbaijan and Israel to be “anti-Iranian”.
Azerbaijan has criticized Iran for supporting Armenia in the decades-long conflict over the breakaway region of Nagorno-Karabakh.
Iran, home to millions of Turkish-speaking ethnic Azerbaijanis, has long accused Azerbaijan of fomenting separatist sentiment in its territory.
The neighbors share a border that runs along the Caspian Sea.
Tensions have risen as Iran normalizes ties with Saudi Arabia, which began last month with a surprise China-brokered deal to restore diplomatic ties that were severed seven years ago.