Spain's "indignants" took to the streets in 80 cities and towns Saturday to decry economic injustice in a show of strength one year after the birth of their movement shook the political establishment.
But the authorities have vowed to stop them camping in Madrid's central Puerta del Sol, the cradle of their popular movement against spending cuts, inequality, bankers and sky-high unemployment.
The marches on Saturday launch a four-day protest that will end on May 15, the anniversary of the movement's birth -- a date that led them to being dubbed 15-M.
The movement, which relies heavily on online social networks to campaign and organise, has inspired similar protests from Britain to the United States' Occupy Wall Street.
In Madrid, several columns of thousands of protesters marched separately on the city centre from all directions. The demonstrators beat drums, blew whistles and chanted slogans as they converged on Puerta del Sol.
"It is important to show that we are still here, that there are thousands of people that want a change and are willing to work for it," said Marina Santos, a 23-year-old office worker who carried a sign that read: "Another World is Possible".
A year after the movement's birth, Spaniards have even more to protest: a recession, unemployment at 24.4 percent, and 52 percent for the young, and more than 30 billion euros ($39 billion) worth of austerity cuts so far this year.
"We are here because we continue to be angry over the austerity policies which an economic elite is imposing on us," said another protester, 21-year-old philosophy student Victor Valdes.
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.
The permit says they must wrap up their activities in the square on Saturday by 10:00 pm (2000 GMT).
But the activists' plans published online call for a minute of silence at midnight and for a "permanent assembly" to be held in Puerta del Sol during the four-day protest.
Deputy Prime Minister Soraya Saenz de Santamaria said the government would ensure that the hours are respected.
"To stay in the square beyond those hours would be a violation of the law and of the rights of other citizens, and this government will ensure the law is respected," she told reporters Friday after a weekly cabinet meeting.
Authorities insist they will 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.
There will be enough police to enforce the law, the government's delegate in Madrid, Cristinia Cifuentes, said Saturday.
"They will ensure there are no encampments because those are illegal activities. You cannot camp in the centre of the city, and I am going to ensure the law is carried out," she told Europa Press news agency.
The "indignants" have staged overwhelmingly peaceful protests and neighbourhood assemblies since their camp at Puerta del Sol was dismantled on June 12 last year, but interest has tapered off.
"The movement has mutated, it is still there. What has happened is that it is not on the streets, it is online and in social networks," said Noelia Moreno, a former spokeswoman for the movement in Madrid.
"This is a long-distance race, no one can change an entire political system in one day or one year, it takes time," the 30-year-old unemployed video producer added.
Critics charge that beyond staging rallies, the movement has had little impact.
Antonio Alaminos, sociology professor at Alicante University, said the "indignants" had failed to organise and were left expressing a discontent born from social and economic malaise without a concrete ideology.
"The result: lots of small relatively disconnected groups that no longer form a social movement," he said.