Protests erupted across several Iranian cities on Thursday in support of Azerbaijan in its conflict with Armenia over the disputed region of Nagorno-Karabakh.

The demonstrations took place in cities including Tehran, the capital, and Tabriz, a city in Iran’s northwest near the Armenia-Azerbaijan border.

Videos posted online on October 1 appear to show dozens of people demonstrating in city streets while chanting slogans in Azeri, a Turkic language. Some of the chants included, “Karabakh is ours. It will remain ours,” Radio Free Europe (RFE) reported on Friday, adding that it could not verify the authenticity of the protest footage.

“Security forces were reported to have dispersed the protesters using tear gas. Clashes were also reported between the protesters and riot police,” RFE relayed.

Iranian authorities detained at least 38 people during the protests, according to the Human Rights Activists News Agency.

Azeris constitute Iran’s largest ethnic minority, with an estimated population of up to 20 million. Like Iran, Azerbaijan is nearly 99 percent Muslim, and both countries have a majority Shia population. Azeris are ethnically Turkic and have been incorporated into Iran’s population since at least the 19th century when a treaty divided Azerbaijan into a northern Russian portion and a southern Iranian portion.

According to RFE on Friday, over “100 people, including many civilians, have been killed since heavy clashes erupted on September 27” between Azerbaijan and Armenia in their disputed region of Nagorno-Karabakh. While the region legally belongs to Azerbaijan, its population is made up of majority Christian Armenians.

After the fall of the Soviet Union in 1991, ethnic Armenian separatists seized Nagorno-Karabakh from Azerbaijan. The uprising caused a war that killed at least 30,000 people. The two sides agreed to an uneasy ceasefire in 1994 to end the war, but sporadic fighting has continued in the region between the countries in subsequent years.

The clashes this week have already evolved into the conflict’s most significant escalation since the ceasefire in 1994, with both sides deploying heavy artillery to Nagorno-Karabakh and accusing the other of firing directly into their respective territory, well beyond the disputed breakaway region.

The representatives of four Iranian provinces with a large ethnic Azeri population released a joint statement in support of Azerbaijan on Thursday, which was endorsed by Iran’s Supreme Leader Ayatollah Ali Khamenei.

The statement said that “there is no doubt” that Nagorno-Karabakh belongs to Azerbaijan, according to RFE.

Similarly, Iranian President Hassan Rohani’s chief of staff told Baku that Tehran recognizes its territorial integrity earlier this week.

“The stance of the Islamic republic on Azerbaijan has always been clear and transparent as it has always recognized the neighboring country’s territorial integrity and respected it,” Mahmud Vaezi told Azerbaijani Deputy Prime Minister Shahin Mustafayev on September 30 in a phone call.

Iran shares a border with both Azerbaijan and Armenia and has officially called for both countries to immediately end hostilities toward each other while expressing its willingness to mediate the dispute.

On Friday, Armenia indicated that it would consider holding peace talks with international mediators to reach a ceasefire, a prospect that both sides had flatly rejected earlier in the week.

“Armenia ‘stands ready’ to engage with France, Russia, and the United States, who co-chair the OSCE [Organization for Security and Co-operation in Europe] group of mediators to the conflict, ‘to re-establish a ceasefire regime’, the Armenian foreign ministry said in a statement on Friday,” according to Al Jazeera.