Baku, Azerbaijan ? Azerbaijani protesters demanding free elections were beaten back Saturday by police, who arrested dozens as they broke up a banned rally in the oil-rich former Soviet republic on the Caspian Sea four days before the inauguration of a new pipeline.

Tension between the government and the opposition in the tightly controlled country has increased since an October 2003 election in which Ilham Aliev replaced his late father, Geidar Aliev, as president in a vote the opposition said was marred by fraud. A parliamentary vote is scheduled for November.

Officials had forbidden the opposition to protest, citing security concerns four days ahead of the visit of foreign leaders who will attend a ceremony marking the opening of Azerbaijan’s portion of the U.S.-backed Baku-Tbilisi-Ceyhan oil pipeline.

The violence broke out as groups of protesters tried to defy the ban and make their way to a central square in the capital, Baku, shouting “Freedom!” and “Free elections!”

Helmeted police with riot shields chased protesters and lashed out at them with truncheons.

Human rights activist Saida Godzhamanly said more than 100 people were detained, including 10 women. Ali Kerimli, head of the People’s Front of Azerbaijan party, said about 300 people were taken off.

The police said 45 people were detained for disorder and refusing to obey police.