Tensions between Iran and Azerbaijan escalated further on Monday when Baku claimed that it had uncovered an “Iranian spy network,” whose members were reportedly arrested.

Azerbaijan’s National Security Services revealed that five Azerbaijani citizens, with alleged ties to Iran’s secret service, were arrested on charges of spying for the Islamic Republic, Azerbaijani media reported.

Earlier this month, Baku announced that it had arrested 17 members of an alleged paramilitary group working in Azerbaijan on Iran’s orders.

The Azerbaijani NSS said that the captain of the Caspian Marine Oil Fleet Zahir Askerov, who was receiving religious indoctrination in Iran’s holy city of Qom, allegedly entered into a secret cooperation with representatives of Iran’s secret services.

On Monday, Azerbaijan’s NSS claimed that Askerov collected and passed information to Iran about foreign companies and representatives of foreign states, as well as the time and place of naval exercises on the Caspian Sea, including cargoes delivered to oil platforms.

Another two Azerbaijani citizens were charged with allegedly photographing oil and gas pipelines, defense ministry and border services drone operations strategic and military facilities, anti-aircraft missile complexes, as well as other radar control facilities located in Baku, Salyan and Fizuli. The other two were charged with allegedly transmitting to Iran information regarding military and intelligence facilities in Azerbaijan.

Official Tehran denied the accusations of employing the alleged paramilitary units.

Tensions between Tehran and Baku have been escalating since the end of the 44-Day War, when President Ilham Aliyev of Azerbaijan began advancing his scheme of create a land “corridor” through Armenia to connect with Nakhichevan. Iran, on several occasions, including through its Supreme Leader Ayatollah Ali Khamenei, has warned of any changes to the sovereign borders of regional countries. Khamenei told the presidents of Turkey and Russia that such an effort would be a “red line.” for Tehran.

Last week, during a speech in occupied Shushi, Aliyev seemingly sent a warning to Iran, which recently held military exercises along its border with Nakhichevan. The Azerbaijani leader also warned Armenia to not pin its hopes on Iran within the context of negotiations with Azerbaijan.

What has irked Iran the most, however, has been Aliyev’s speech during the Organization of Turkic States summit. There, Aliyev said access to native language, traditions and culture for Turkic people’s living outside of those countries must be guaranteed. He went on to point out that more than 40 million Azerbaijanis are deprived of that right, presumably referring to that many ethnic Azerbaijanis who live in Iran.

The Deputy Speaker of Iran’s parliament Ali Nikzad on Sunday fired back at Aliyev by saying that “the grandson cannot deny the existence of his grandfather, therefore, the statements of the President of the  Republic of Azerbaijan are groundless.” This comment was made in line with Iran’s insistence that Azerbaijan would not exist as a country if it weren’t for Iran’s efforts.

Alborz Hosseini, another lawmaker, in turn, advised Aliyev to  read the Gulistan peace treaty in order to understand the history of  the country. He stressed that the President of Azerbaijan has no  right to make such statements about the territorial integrity of  neighboring countries.

“The statements of the President of Azerbaijan are groundless. If the Gulistan peace agreement was not reached, then the Republic of Azerbaijan would be a part of Iran  and he would not have become the president of this country. The  Iranian Foreign Ministry and Parliament should respond to such  statements, because the region needs peace more than ever,” Hosseini said.

Mohammadreza Mir-Tajedini, the lawmaker representing the  city of Tabriz in Iranian Azerbaijan, also commented on Aliyev’s  statements, noting that Azerbaijan had separated from Iran, and “if we are talking about accession, then Nakhichevan should join Iran.”