Powerful cyber attack spreading around world

A powerful cyber attack has spread across the globe, hitting some of the world's biggest companies.

The attack spread across Europe overnight, with Danish shipping company AP Moller-Maersk and Russia's Rosneft oil company reporting their systems had been hacked, AP reported.

Major firms in the UK, Europe, Russia, France and Germany have been affected.

Ukraine appeared to be the most severely hit, with Prime Minister saying the attack was "unprecedented".

New Zealand's government cyber safety authority Computer Emergency Response Team (CERT) has not yet had any reports of ransomware attacks, but offered security advice through its website.

CERT said on Twitter on Wednesday morning it was aware of the cyber attack and asked for anyone affected to come forward.

It's not yet known who is behind the attack, which appears to be similar to the WannaCry hack in May.