Jeddah A Saudi court has sentenced 11 men to up to 15 years in prison for membership of a cell linked to Al Qaida that planned to attack US forces in Kuwait and state-owned Saudi oil giant Aramco, Saudi media reported on Wednesday.

The 11 were among thousands of people rounded up as the world's top oil exporter battled al Qaeda militants between 2003 and 2006.

Al Riyadh newspaper said the sentences, handed down by the Specialised Criminal Court in the Saudi capital on Tuesday, ranged from two to 15 years in jail.

"The verdicts ... include 15 years in prison for the first defendant for joining a terror cell which targeted American forces in Kuwait and important Aramco sites," the newspaper said.

A spokesman from the Justice Ministry could not be reached for comment.

Last year, the Interior Ministry said 5,696 people had been detained by the authorities in "militant" cases, of whom 5,080 had already appeared in court.

Human rights groups say peaceful political activists have also been imprisoned in the kingdom's crackdown on militants.

Only the government's Human Rights Commission (HRC), which reports to Saudi King Abdullah, and selected Saudi media can attend the trials, HRC and independent human rights campaigners said, demanding they be opened to a wider audience.

"The trials have to be open and transparent. In the absence of transparency I am not aware if there was due process," the president of the kingdom's Human Rights First Society, Ebrahim Al Mugaiteeb, told Reuters.

Last year a Saudi court gave 16 men long prison sentences for "funding terrorism" and conspiring with Al Qaida to seize power.

Rights campaigners say the men had been peaceful activists for a constitutional monarchy and other reforms.