A statement purported to be from the al-Qaeda chief in Saudi Arabia and posted on a militant website on Thursday urged his followers to wage an urban guerrilla war of assassinations, kidnappings and bombings.

The "execution group" or "strike force" in each four-tiered cell should be "trained to carry out operations inside cities, including assassinations, abductions, bombings, sabotage, raids and the liberation of hostages," said the statement attributed to Abdul Aziz al-Muqrin and posted on www.qal3ah.org.

The lengthy statement, the authenticity of which could not be independently confirmed, appeared to be several months old. It was not clear why it was made public now. It refers to the Saudi authorities’ announcement "in recent days of the names of 26 Mujahid (fighter) ... which showed the failure of their security agencies to track down the Mujahideen."

The reference was to a list of 26 most-wanted terror suspects issued by Saudi authorities in December following a series of suicide bombings that targeted residential compounds in Riyadh in May and November 2003.

Muqrin tops the list of presumed al-Qaeda militants, which is now down to 18. In the statement, Muqrin said each guerrilla cell should be composed of four groups: a field command, an intelligence-gathering group, a third assigned to prepare the equipment and groundwork for operations, and a fourth that would execute the attacks and would be made up of two to four members.

"In a country which has no places suitable for action such as mountains and forests, one should suffice with urban forces and collaborators," the statement said. Militants "need a strong Islamic intelligence apparatus to confront the dangers surrounding clandestine action in cities," it said.

The guerrillas in charge of preparing operations should include people "with links to the Mafia or other smugglers, because the latter have experience and can be very useful," the statement said.