Global

International law firm DLA Piper has told Australian employees it has been the victim of a "major cyber incident" overnight.

Its Washington DC office was apparently affected, and Australian staff were advised via text early this morning that all IT systems had been taken down to contain the situation.

The Cadbury chocolate factory in Hobart has also been targeted, the ABC has reported.

A union official said production at Cadbury's Claremont facility was halted when the computer system went down about 9.30pm yesterday in what was described as a "cyber-attack".

Europol has also warned a "complex international investigation" was required "to identify the culprits".

It's emerged that the tools used in the attack appear to have been stolen from the US National Security Agency.

There have been reports of infections in as many as 100 countries, including several in New Zealand, a live-tracking map of the attack showed.

European countries, including Russia, were among the worst hit.

Although the spread of the malware - known as WannaCry and variants of that name - appears to have slowed, the threat is not yet over.