RIYADH (Reuters) -Four suspected al Qaeda members arrested in Saudi Arabia last year had planned to attack the kingdom’s oil facilities and other Gulf Arab oil producers, they said in confessions shown on Saudi television on Tuesday.

Saudi police arrested the four in April last year in connection with a failed attack two months earlier on Abqaiq, the country’s biggest oil-gathering facility.

Saudi Arabia is the world’s biggest oil exporter, supplying about 7 million barrels per day, and holds almost a quarter of the world’s oil reserves.

“Targeting the main oil facilities and areas, such as Ras Tanura and Jubail, was how the idea started,” a cell member, identified as Abdullah al-Muqren, said in his confession.

Ras Tanura is Saudi Arabia’s biggest oil export terminal and Jubail its biggest industrial complex. Both are on the Gulf coast.

“We started planning (for the attack) but were told to wait for direct instructions from sheikh Osama bin Laden. I asked how would we receive a signal from him, I thought he was in some mountains. They (Qaeda) said: it will take from six to seven months to get his approval.”

“They were planning for more strikes in more than one place towards Kuwait and the United Arab Emirates.”

Another suspect, identified as Khaled al-Kurdi, said al Qaeda leadership in Saudi Arabia told them that the attacks on oil facilities would be “equal” to the September 11, 2001 attacks.

“They said it will be a huge operation, equal to the September strike… and its impact will be on a global level,” Kurdi said in his statement aired by a Saudi state television.

“They said attacks will affect oil prices.”

Saudi security sources have said the men were involved in providing logistical help to the attackers who tried to storm the Abqaiq facility in February 2006, in which two suicide bombers were killed.

Saudi Arabia arrested 170 suspects after the attacks.

Islamist militants swearing allegiance to al Qaeda launched a violent campaign to topple the U.S-allied Saudi monarchy in 2003, carrying out suicide bomb attacks on foreigners and government installations, including the oil industry.

Tough security measures and a publicity campaign helped quell the violence but analysts and diplomats have said the underlying currents of radical Islamist ideology and anger at Western policy in the region remain strong.