The protesters fled when the police moved in to disperse them

Hundreds of people, the majority of them young men and women, joined the protest on Tuesday which took place close to where the Saudi Government was hosting its first human rights conference.

Reports said the police fired shots into the air to disperse the crowd, who were led by bearded men chanting "God is great".

The BBC's Middle East analyst, Roger Hardy, who is in Riyadh, says that such public protests are a rarity in the conservative kingdom, where opposition of any kind is banned.

He says the demonstration has greatly shaken the establishment.

The government was quick to dismiss the impact of the protest.

"What happened was just a limited gathering in al-Olaya street. They are a small bunch ... this won't happen again," the country's Interior Minister Prince Nayef bin Abdul Aziz said, according to the official Saudi Press Agency

Demonstrations are the behaviour of non-Muslims Grand Mufti Abdul-Aziz bin Abdullah Al al-Sheik

But the organisers from the UK-based Movement for Islamic Reform in Arabia (MIRA) - say that even more citizens had been keen to join the demonstration.

"If the peaceful protest which we called for was not savagely suppressed, tens of thousands of people would have participated," MIRA spokesman Saad Faqih said.

Elections promise

Saudi Arabia's highest religious authority the Grand Mufti Abdul-Aziz bin Abdullah Al al-Sheik condemned the incident saying "demonstrations are the behaviour of non-Muslims".

"Their demands must be made through proper ways," he warned.

The demonstrators chose one of the most prominent skyscrapers in Riyadh - the Kingdom Centre - as the site of their protest.

Pressure is great on the Gulf monarchy to reform

And the high profile inaugural human rights conference - which opened on Monday and coincided with an announcement by the Saudi authorities that they would hold the first council elections.

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.