Azerbaijan on Thursday arrested six men it said were linked to Iranian secret services and were plotting a coup in the Caspian nation, in the latest tensions between Baku and Tehran.
Relations between the neighbours have long been strained, with Azerbaijan being a close ally of Iran's historical rival Turkey.
The arrests came after months of diplomatic tensions.
Baku said the six Azerbaijani nationals were "recruited by Iranian secret services to destabilise the situation in the country".
It announced the arrests in a joint statement by the interior ministry, state security service and prosecutor-general's office.
It said the group was plotting to "set up a 'resistance squad' aimed at establishing a Sharia state in Azerbaijan through armed unrest and violent overthrow of Azerbaijan's constitutional order".
It accused them of being "engaged in a pro-Iranian propaganda of religious radicalism, fulfilling orders from abroad to undermine Azerbaijan's tradition of tolerance".
According to Azerbaijan, they promoted "radical Islam" using money from drug profits.
In January, Azerbaijan suspended the operation of its embassy in Iran, days after a gunman stormed the mission, killing one guard and wounding two others.
Baku has claimed that Tehran's secret services were behind the attack.
Last year, the oil-rich country arrested five of its nationals for spying for Iran and 17 more men who Baku claimed belonged to an "illegal armed group set up by Iran."
Azerbaijan has criticised Iran over allegedly backing Armenia in Baku's decades-long conflict with Armenia over the breakaway region of Nagorno Karabakh.
Iran — which is home to millions of Turkic-speaking ethnic Azerbaijanis — has long accused Azerbaijan of fomenting separatist sentiment inside its territory.
Tehran also fears that Azerbaijani territory could be used for a possible offensive against Iran by Israel, a major supplier of arms to Baku.
The neighbours share a border that runs near the Caspian Sea.
