Police in the Saudi capital, Riyadh, have broken up a rare demonstration which was calling for political reform.
Reports say police arrested dozens of protesters
The protest took place close to where the Saudi Government was hosting its first human rights conference.
Reports said police fired shots into the air to disperse a crowd of a few hundred people, who were led by bearded men chanting "God is great".
A number of arrests were made after what eyewitnesses describe as minor scuffles with the police.
It is not clear what the aim of the rally was, but it came after an exiled Saudi opposition group - the UK-based Movement for Islamic Reform in Arabia (MIRA) - had said it planned a sit-in against the detention of government opponents.
The official Saudi Press Agency (SPA) later described the protest as "a rally by a number of individuals" which disrupted traffic in a busy district of Riyadh.
"The police immediately dealt with this gathering in accordance with security duties and returned traffic to its
normal course," SPA said.
Opposition of any kind is banned in the conservative kingdom, and experts say the incident is deeply embarrassing for the Saudi Government.
The conference - which opened on Monday - coincided with an announcement by the Saudi authorities that they would hold the first council elections. The move is being seen as the first political reform in the country.
The demonstrators chose one of the most prominent skyscrapers in Riyadh - the Kingdom Centre - as the site of their protest.
Saudi Arabia's record on human rights has been heavily criticised
Eyewitnesses say the protesters of different ages - including women - converged on the building at about 1600 local time (1500 GMT).
After anti-riot police armed with batons intervened to break up the rally, the protesters tried to regroup but were chased away.
The BBC's Roger Hardy in Riyadh says the whole thing was over in less than two hours.
Our correspondent says that one eyewitness told him that the demonstration was important because it was the first time such a thing had happened in the heart of the Saudi capital.
The eyewitness said he did not support the demonstrators, but understood their frustration over unemployment and the lack of free speech in Saudi Arabia.
However, he said that he wanted reform but of the liberal kind, not the sort of reform the bearded protestors were calling for.
Saudi Arabia has long been criticised by the international community for its poor record on human rights and has recently tried to made a number of steps to alter this perception.
Pressure is great on the Gulf monarchy to reform
The new criminal code forbids torture and suspects are now allowed to have a lawyer present during their questioning and trial.
Citing a desire to "widen the participation of citizens in running local affairs", Saudi authorities also announced their decision to hold council elections, through which half of future council members will be elected, state news agency SPA reported on Monday.
The desert kingdom has not had political elections at any level since its creation in 1932.
Although human rights groups have welcomed such reforms, they say that in practice the Saudi legal system is still deeply flawed.
New York-based group Human Rights Watch says thousands of people are still being held without trial, there is no free press and women are forbidden to drive.
But BBC correspondent Frank Gardner says optimists have pointed out there is some progress.
Even a few years ago, simply holding a human rights conference inside the country would have been unthinkable, our correspondent says.