A Saudi court has sentenced 13 men to up to 14 years in prison for security offences including material support to wanted Islamist militants, aiding terrorism and helping young men go to Iraq, Syria and Afghanistan to fight.

The conservative Islamic kingdom has sentenced thousands of its citizens to prison terms for similar offences over the past decade since al Qaeda waged a campaign of attacks from 2003-06 inside the country, killing hundreds of people.

But the growing role of militants in Syria has raised fear in Riyadh about a new wave of radicalism among its own citizens and the government has issued stern new penalties for fighting abroad or supporting groups it says are extremist.