Dozens of Iranians have demonstrated outside Azerbaijan's consulate in the northwestern city of Tabriz to protest the alleged "killing of Shia" in Nardaran, a suburb of the Azerbaijani capital of Baku, Iranian news agencies reported on December 10.
The reports said protesters accused the Azerbaijani authorities of repressing the Shi'ite community in the oil-rich former Soviet republic.
Photographs from the December 10 protest show men and women outside the consulate holding placards with names and pictures of individuals described as "Nardaran martyrs" as police guard the compound.
Nardaran, known as a traditional Shi'ite Muslim stronghold, has been the site of recent deadly clashes and security operations by Azerbaijani authorities.
The semiofficial Mehr news agency said the protest was "spontaneous" and included students from seminaries and other institutes. After the demonstration, participants reportedly staged prayers and mourned in front of the consulate.
Spontaneous protests are rare in Iran, where only pro-government demonstrations are typically allowed.
Azerbaijani authorities said two police officers and four suspected militants were killed during a November 26 raid on a "criminal gang" that was allegedly planning terrorist attacks in the country.
A December 1 raid in Nardaran resulted in the death of at least five suspected Shi'ite militants and two police officers.
The detainees in the crackdown have included Taleh Bagirzadeh, the leader of a group called the Movement for Muslim Unity who received his education in Iran.
Azerbaijani authorities said the operation was aimed at "protecting citizens' legal rights and freedoms" and confiscating weapons and explosives from "criminals."
While Azerbaijan is a Shi'ite-majority country, Nardaran is home to Iranian-influenced fundamentalists often seen as being at odds with the secular government in Baku.
Many women in the village wear the full Islamic veil, and girls wear the hijab, or head scarf, to school despite a national ban.
The raids in Azerbaijan have been criticized by a group of Iranian lawmakers who condemned the "martyrdom of a number of Nardaran's Shia."
Ayatollah Mohammad Mojtahed Shabestari, the leader of Friday prayers in Tabriz, said last week that the actions of Azerbaijani forces in Nardaran cannot be tolerated.
"The situation of Nardaran's people is very worrying. The government of Azerbaijan accuses the Islamic republic of having a hand in the unrest, while the Islamic republic has always adhered to good neighborly ties with this country," Shabestari was quoted as saying on December 4 by the hard-line Fars news agency.
In a statement issued December 1, Iran's embassy in Baku said Iran "has never" meddled in Azerbaijani's internal affairs and "did not play any role in the events in Nardaran."
Tensions between Azerbaijan and Iran have repeatedly flared in recent years.
In 2012, Azerbaijani authorities arrested several men with purported ties to Iran who allegedly plotted to stage attacks in Azerbaijan.
Azerbaijan has jailed several of its citizens after convicting them of spying for Tehran since 2012.
Baku's warm ties with Israel have also been a source of tension in its relations with Iran.