Police in the Kenyan capital, Nairobi, fired tear gas to try to disperse protesters who were protesting on Monday against what they said was the mysterious kidnapping of government critics and to keep some of them from participating.
Dozens of Kenyans have been abducted in recent months, according to human rights groups, who accuse the Kenyan police and intelligence services of illegal arrests.
Kenyan authorities say the government does not encourage or engage in extrajudicial killings or kidnappings.
Some groups of small protesters marched in downtown Nairobi while small groups of others sat in as a cloud of teargas hung in the air. They said words against the government, some carrying iiplacards declaring illegal detention as police on horseback patrolled nearby.
Among the protesters was opposition party representative Okiya Omtatah, who was taking part in the rally, with protesters using heavy chains to hold them while riot police tried to arrest them.
Kenya's Daily Nation newspaper reported that Omtatah and 10 other protesters were arrested during the protest.
Nairobi police commander Adamson Bungei and national police spokeswoman Rosalia Onyango did not respond to requests from Reuters.
The alleged kidnappings follow anti-government protests that began in June this year.
Initially aimed at overturning proposed tax hikes, the protests eventually turned into a movement that cut across Kenya's national borders, becoming the biggest threat to the ruling government of William Ruto.