* Saudi says activists used "false information"
* Growing number of small protests over detentions
By Angus McDowall
BURAIDAH, Saudi Arabia, March 8 (Reuters) - Saudi Arabia on Thursday accused online activists of using social media to stir up protests, banned in the kingdom, by distributing "false information" about the number of people detained by the security apparatus.
Concern over the fate of the kingdom's thousands of security detainees, who the government says are Islamist militants, has prompted demonstrations, culminating in the arrest of 161 people at a protest last week in the central city of Buraidah.
The accusation, delivered during a news conference in Buraidah, underscored the government's concerns over the impact of reports distributed via social media that many long-term detainees have not been brought to trial, and that police treated women protesters disrespectfully.
Last week's protest was the latest in a string of demonstrations by relatives of detainees in the capital Riyadh and Qassim Province, heartland of the kingdom's ultra-conservative Wahhabi school of Islam.
In January more than 100 Wahhabi clerics wrote to King Abdullah, pressing him to address the issue swiftly, a significant step given the paramount role of religion in Saudi society and top clerics' backing of the protest ban.
"There are people who misuse the social networking and try to send false information," Maj. Gen. Mansour Turki, the Interior Ministry's security spokesman, said.
"They use (it) to make some families go outside and try to protest, saying you should release our husbands or our fathers or our sons," he added.
Families of some detainees say their jailed relatives have been held for years without charge or trial, have been mistreated while in detention or continue to be held after their sentences were completed.
Human rights activists say people who merely called for political change or elections have been jailed on the same grounds, something the authorities deny.
Al Qaeda launched a series of deadly attacks against foreigners and government targets from 2003-06, prompting a heavy crackdown on Islamist militants. Al Qaeda's regional wing, now based in Yemen, has sworn to end al-Saud rule.
Turki said 2,772 people were now held in security prisons. One local human rights activist, whose trial for "electronic crimes" will reach a verdict on Saturday, previously had estimated the figure was as high as 30,000.
In last week's protest in Buraidah, some protesters burned photographs of the interior minister, King Abdullah's nephew Prince Mohammed bin Nayef, underscoring the strong emotions the issue evokes.
The move was almost unprecedented in a country named for the al-Saud dynasty and where most businesses still display portraits of the king and crown prince.
"People here in Qassim are angry with the Interior Ministry. People have died in prison. People have gone mad in prison. But thank God the clerics in Qassim are all good. They have spoken on our behalf," said Huda al-Araini, whose husband has been held for nine years.
Turki said activists had pushed detainees' relatives who had attended the protests to lie about their treatment by police.
"Some people... try to make some of the protesters go and accuse the policemen of mistreating them or being very offensive when they deal with them," he said. (Reporting By Angus McDowall; Editing by Michael Roddy)