Several government websites in Saudi Arabia were hacked in a series of heavy cyber attacks from overseas in recent days, disabling them briefly until the attacks were repelled, the government has 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 SPA, the country's state news agency.

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 almost 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 claim that they support Syrian President Bashar al-Assad.

PHOTO CAPTION

A cyber attack on Saudi Aramco, the world's biggest oil company, damaged almost 30,000 computers last year [AP]

Aljazeera