Prime Minister John Key says he tends to use a private email address, despite the fact that Foreign Minister Murray McCully had a private email account hacked into.
Mr Key confirmed yesterday that the hacking occurred in April last year.
But he said Mr McCully's office had advised him that there had been no classified material on the private email address.
Mr McCully told the Dominion Post he discovered the breach when people started receiving emails from the Telecom Xtra account making fun of himself.
It had been closed down.
The hacking was reportedly the work of the Anonymous collective, which recently attacked the United States Department of Justice and the FBI after raids on the home of Kim Dotcom in Coatesville near Auckland, and the closure his Megaupload website.
Mr Key told reporters yesterday he had told MPs to be very careful about security.
Whether MPs used private addresses depended on the individual.
"I have quite a number of emails but because I have my electorate office and others I tend to use a private email address."