Militants linked to al-Qaeda on Sunday renewed a threat to attack Saudi oil supplies, in a defiant challenge to the intense security put in place to defend the kingdom's production facilities.

Security experts said Sunday’s statement from the “Al-Qaeda Organisation in the Arabian Peninsula” built on a threat issued on Friday by Osama bin Laden, the al-Qaeda leader. He called for attacks on oil facilities in Saudi Arabia, the world's largest producer. Crude futures on Nymex rose almost 5 per cent to $46.28 a barrel on Friday, partly in response to the statement. Yesterday's threat, dated December 18 and issued on an Islamic website, said: “We call on all the mujahideen in the Arabian Peninsula to unify their ranks . . . and target the oil supplies that do not serve the Islamic nation but the enemies of this nation.”