RIYADH (Reuters):

Saudi Arabia said yesterday it foiled an al-Qaida-linked plot to attack oil facilities and military bases, arresting more than 170 suspects, including some trainee pilots preparing for suicide operations.

The Interior Ministry said police seized weapons and more than 20 million riyals (US$5 million) in cash, from seven armed cells.

"Some had begun training on the use of weapons, and some were sent to other countries to study aviation in preparation to use them to carry out terrorist operations inside the kingdom," a ministry statement said.

"One of their main targets was to carry out suicide attacks against public figures and oil installations and to target military bases inside and outside (the country)."

Saudi Arabia is the world's top oil exporter, supplying about 7 million barrels a day to world markets. It holds nearly a quarter of the world's oil reserves.

News of the arrests helped push oil prices up by around 52 cents a barrel to $68.17 just after 1600 GMT. Al-Qaida has called for attacks on oil targets.

Most of the 19 al-Qaida militants who commandeered hijacked planes in the September 11 attack on the United States were Saudis.

violent campaign

Islamist militants swearing allegiance to al-Qaida 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.

"The deviant group is still trying to revive its criminal activities in the kingdom," Interior Ministry spokesman Mansour al-Turki told state television.

Analyst Fares bin Houzam, a former militant sympathiser, said the arrests showed the failure of the government's campaign to demonise the militant movement.

"This suggests that over the last four years not much has been achieved. Security forces find groups, but at the ideological level progress is very slow," he told Reuters.