An investigation has been launched after hackers took down several Government websites this morning.
No one has yet claimed responsibility for the cyber attacks that affected sites including the CSO, the Oireachtas and the HSE. The sites are up and running again.
It is thought they were targeted by DDos attacks, where sites are overwhelmed with traffic.
Paul Hogan from tech firm Ward Solutions said the motive remained unclear.
"Motivations can include political, or 'hacktivism', or fraud," he said. "Sometimes organisations use these DDos attacks as a cyber smokescreen to mask a more targeted attack."