Hundreds of supporters of an Azerbaijani opposition party rallied in the capital, demonstrating against a referendum later this month that seeks to strengthen President Ilham Aliyev’s authority.
Baku city police reported no major problems with the September 18 rally by the Musavat party, which ended after about two hours.
"Azerbaijan now finds itself in a crisis situation due to the incorrect policies of the Aliyev regime. We urgently need reforms in the country," Arif Gadzhili, a top party leader, told the crowd holding Azerbaijani flags and photographs of people believed to be political prisoners.
"However, the Aliyev regime, which has concentrated power in one hand, is conducting policies that are aimed at putting yet more power in that hand," he added.
The rally had been authorized by government officials.
The September 26 referendum has generated sharp criticism from Azerbaijan's beleaguered opposition, as well as civil society activists, journalists, and others.
Critics say the referendum will tighten Aliyev's grip on power, which he has held since 2003 after inheriting the presidency from his father, Heydar.
The September 18 rally was a noticeable contrast to a demonstration held a day earlier in Baku, during which police and protesters clashed. The demonstrators were also protesting the upcoming referendum.
Several journalists were also detained by police during the clashes, including at least two freelancers working for RFE/RL's Azerbaijani Service.
One RFE/RL journalist was taken from the scene of the protest in a bus with some 30 detainees.