Several government websites in Saudi Arabia were sabotaged in a series of heavy cyber attacks from abroad in recent days, disabling them briefly until the attacks were repelled, the government said.
An investigation traced the "coordinated and simultaneous attacks" to hundreds of Internet protocol addresses in a number of countries, an unnamed source at the Saudi Interior Ministry told state news agency SPA.
The interior ministry website crashed on Wednesday after it received a "huge amount" of service requests, but was back online less than two hours later after the "necessary technical drills" were performed to counter the attack, the source said.
The report made no mention of a possible motive.
Businesses, government agencies and critical infrastructure operators face unprecedented challenges from increasingly sophisticated cyber attacks launched by criminals, hacker activists and foreign governments.
An attack last year on national oil company Saudi Aramco - the world's biggest oil company - damaged some 30,000 computers and was one of the most destructive cyber strikes conducted against a single business.
That attack used a computer virus known as Shamoon. A group that claimed responsibility said Saudi Aramco was the main source of income for the Saudi government, which it blamed for "crimes and atrocities" in several countries including Syria and Bahrain.
On Friday, the website and Twitter feed of the Financial Times newspaper were hacked, apparently by the "Syrian Electronic Army", a group of online activists who say they supported Syrian President Bashar al-Assad.