Two senior editors of Sputnik media outlet and an editor of video news outlet Ruptly were arrested by the Azerbaijani government on June 30.
Speaking to reporters after the arrest, Russian Foreign Ministry spokeswoman Maria Zakharova said that "faced with Baku's hostile actions and the illegal detention of Russian journalists, the Ambassador of the Republic of Azerbaijan was summoned to the Ministry of Foreign Affairs on July 1".
Zakharova expressed concern that Russian diplomats "cannot contact detained journalists who are Russian citizens".
Dmitry Kiselev, head of Russia Today's Rossiya Segodnya media group, where Sputnik is headquartered, described the arrest of Russian journalists in Baku as an "unfairness".
"There are no objections to Sputnik Azerbaijan's press activities," Kiselev affirmed, adding that Russian and Azerbaijani officials have agreed to resolve "formal procedures" related to the activities of the Russian media agency at a meeting in Moscow in early April. However, Baku is accused of slowing down the process.
Mr. Kiselev expressed skepticism about the way Azerbaijani police treated Russian reporters, "as if they were terrorists".
He noted that the treatment of reporters is completely opposite to the nature of the relationship between Russian President Vladimir Putin and Azerbaijani President Ilham Aliyev.
Previously, on June 30, Sputnik confirmed that Editor-in-Chief Igor Kartavykh and Editor-in-Chief Evgeny Belousov had been arrested by Baku police. Both were accused of being spies of the Russian Federal Security Service (FSB) - a statement that the Russian media agency denied as unreasonable.
At the end of the day, a third Russian journalist, who worked for video news agency Ruptly, was also detained by Baku police.
Relations between Russia and Azerbaijan have deteriorated in recent days, following a police raid in the Russian city of Yekaterinburg, targeting suspected members of an Azerbaijani criminal group and arresting several individuals.
According to the Russian Investigative Committee, two suspects died during the raid, one died of a heart attack, the other died of an unknown cause.
According to Russian authorities, the group is suspected of being behind a number of murders since the early 2000s.