Saudi cyber experts held urgent talks on Tuesday after government facilities were hacked, official media reported.
The cyber attacks "in recent weeks targeted government institutions and vital installations in the kingdom," the Saudi Press Agency reported, without identifying the targeted agencies.
It said the kingdom's Cybersecurity Centre "held an urgent workshop with a number of parties" to discuss the results of its investigations.
The attacks originated abroad and subjected users' accounts to viruses which spy on information, it said.
Experts outlined how the attacks occurred and presented "necessary procedures to fix and to protect those sites", Saudi Press Agency said.
It gave no indication as to the source of the hacking.
In June a major Saudi newspaper said hackers briefly seized control of its website to publish false information.
Four years ago, a damaging malware assault hit the state oil company Saudi Aramco. US intelligence officials believed it was linked to Iran.