National's Nuk Korako is apologising for a number of tweets sent out from his personal account by his son and nephew.
The pair commandeered his phone while Mr Korako was at a briefing about the Christchurch fires, and starting replying to a handful of people.
"I was sitting on the wharepaku (toilet) dropping the kind of stuff you and your mates put on Twitter," one of the messages said.
Another message was sent to former Labour candidate James Dann and asked: "Why are you breathing?"
"I'd better put Dad's phone back as I've had my fun now. No wonder he never responds to you dicks," said another.
Mr Korako says he's given the two family members a grilling about it.
"That behaviour was unacceptable and I've spoken to them. I've really spoken to them strongly and I apologise for any offence caused.
"I take full responsibility for it. I should've ensured my phone was secure, but around family you drop your guard a bit," he says.
He didn't know about the messages until his executive assistant in Wellington rang him.
The tweets have since been deleted.