Bahraini police used tear gas to disperse dozens of Shiite protesters who tried to gather on Friday in the capital Manama to demand the release of jailed opposition figures, witnesses said.
The protesters, who came in small groups in the old quarter of the capital, were prevented from converging on a main road where they intended to march.
Some carried banners reading "Freedom for the prisoners" and "We want an independent judiciary," according to witnesses, who said Sheikh Ali Salman, the head of Al-Wefaq, the main Shiite opposition formation, was present.
The interior ministry said the protest was prohibited and that any participants were breaking the law.
The protesters aimed to demonstrate against a Tuesday appeals court verdict, which upheld jail sentences against 13 leading activists, including seven facing life in prison.
The Sunni-ruled kingdom, home to the US Fifth Fleet and strategically situated across the Gulf from Iran, has continued to witness sporadic Shiite-led demonstrations, mostly outside the capital, since it crushed a protest movement in a bloody crackdown in March of last year.
On Tuesday, Amnesty International called the verdicts "another blow to justice," adding that they showed "once more that the Bahraini authorities are not on the path of reform but seem rather driven by vindictiveness."