More than a thousand demonstrators returned to a central Madrid square Sunday to demand the release of 18 people who were arrested earlier during an "Indignant" movement protest.
Spanish police had made the arrests early Sunday as they cleared the Puerta del Sol square after issuing an official warning to disperse late Saturday.
The square has become a focal point for Madrid's Indignant demonstrators, and many had spent the night there as part of nationwide rallies to mark a year since the inception of the movement that helped inspire similar protests worldwide.
A police spokeswoman told AFP that aside from the 18 arrests, two police officers had been injured.
Those arrested were due in court Monday. Supporters waved their hands in the air and held a minute-long "silent scream" to demand their release.
"We are protesting peacefully to defend our rights," said Carolina Hermoso, 36, who works in public education. "We aren't terrorists, wht are there so many police here? We are peaceful," she added.
Police soon cleared about 200 demonstrators from the square.
Over the weekend, Spain saw thousands of Indignant demonstrators pour into streets around the country. Madrid police estimated about 30,000 people had taken part in the protest Saturday.
In Barcelona, Spain's second city, the turnout was 45,000, according to police, and 220,000 according to organisers.
The marches, held in 80 cities and towns across Spain, launched a four-day protest that will end on May 15, the anniversary of the movement's birth -- dubbed 15-M.
While Barcelona city hall seemed prepared to tolerate a camp for a limited period, the authorities in Madrid insisted they would not allow a repeat of last year's month-long sprawling encampment in Puerta del Sol that included everything from a canteen to a kindergarten and a library.
Spain's conservative government, in power since December, has issued a permit for the Indignants to use Puerta del Sol for a five-hour assembly Saturday and for 10 hours on each of the following three days.
Deputy Prime Minister Soraya Saenz de Santamaria said the government would ensure the regulated hours were respected.
Early Sunday, police in Palma cleared about 100 demonstrators and dozens more in Valencia, local media said.