In a speech before hundreds of clerics, Prince Nayef bin Abdulaziz appeared to suggest that some members of Saudi Arabia’s powerful religious establishment had not doing enough in the fight against militants who are warring against Western influence in the region.

“Do you know that your sons who go to Iraq are used only for blowing themselves up? Iraqi officials told me that themselves,” the leading member of the royal family said in comments carried by state media.

“They are brought to put on explosive belts or blow themselves up in cars … Innocents die. Are you happy for your children to become instruments of murder?” he added.

There have been reports in Saudi Arabia about sons of some prominent Saudi clerics trying to get into Iraq to join Al Qaeda insurgents fighting US forces and the US-backed Iraqi government.

Authorities often cite the danger of Saudi militants returning to the kingdom to join militants who have led a campaign of suicide bombings and attacks against government installations, energy sites and foreigners since 2003.

Around 264 people have died in the violence, which has tailed off since a failed attempt in February 2006 to storm a major oil facility in Abqaiq.

In April the government announced the arrest of 172 men who were described as being part of a major plot to revive the militant campaign, involving men and money from Islamists fighting in Iraq.

“You have a big responsibility and you must shoulder it. We must feel your work and effort on the ground. You will be rewarded by God and everyone in this country will thank you, not least its rulers,” Prince Nayef said.

“Preventive measures have foiled over 90 per cent of the actions of these errant people,” he said.

“Let’s imagine that they had succeeded with 30 percent of their acts … We would be in a very bad situation, one we wouldn’t even wish for our enemies,” he added, citing violent civil conflicts in Muslim countries.