Cuban government agents have detained about 20 female dissidents trying to highlight International Human Rights Day, halting the demonstration before it started.
The opponents were taken away in cars and buses on Tuesday afternoon after their planned protest along a central street in Havana was interrupted.
International rights groups say Cuban laws virtually prevent all forms of protest and dissent.
Under former President Fidel Castro dissidents often faced long prison terms for their activities, while under his brother Raul, who took over in 2008, the government has changed tactics, temporarily detaining opponents for a few hours, days or weeks and then releasing them, only to repeat the process if they protest again.
The activists detained on Tuesday were members of the Ladies in White group, formed by the wives and mothers of 75 dissidents jailed in a 2003 crackdown on Fidel Castro's opponents. The men have since been released, but the organisation has continued to protest what it views as human rights violations by the government.
The women, in groups of two or three, came in taxis over a 20 minute period, in an apparent attempt to avoid police, but to no avail.
Meanwhile, pro-government demonstrators gathered in the street to shout slogans for the Cuban revolution.
The government marked the day by organising a human rights forum that celebrated its achievements in providing citizens with social services and protections.
International Human Rights Day marks the 65th anniversary of the adoption of the Universal Declaration of Human Rights by the United Nations.