KEY POINTS:
Breakfast host Paul Henry is involved in a spat with National MP Murray McCully over claims Henry called him a "stupid old man" during the show.
The row started last month when McCully filed a series of complaints with TVNZ.
It took a twist last week when Henry called McCully his "nemesis" on air and questioned the signatures on letters from the MP.
On Thursday, Henry, a former National Party candidate who lost to Georgina Beyer in Wairarapa in 1999, pointed a handheld camera at the signatures and told viewers: "There are some similarities but they're pretty far and few between."
He then questioned McCully's honour and said he "probably has a rubber stamp" to sign his name.
McCully said the tussle started a few weeks ago when Henry made fun of his age.
"Paul Henry was taking a shot at John Key a couple of weeks ago and he called me a stupid old man. So I wrote in a tongue-in-cheek sort of letter to him suggesting that calling me old and stupid was unbalanced.
"It said things like `notwithstanding my weary demeanour, I am actually only 55 years of age, and I would hardly call that old', and things like that. It was tongue-in-cheek but he was a bit rough.
"I thought he was doing it a bit too much," said the East Coast Bays MP, who did not return subsequent calls about the signature allegations.
Henry told the Herald on Sunday he "has no idea" how the spat started and did not remember calling McCully an old man.
"I've made fun of him over the years and I'd heard that there were a couple of complaints from him about me," said Henry.
"I had a look at the letters from his office, signed by him, and I was simply pointing it out because they are so completely different."
Despite the jibes Henry said he didn't want it to sound like he was attacking McCully because he was National.
"It's just because he's Murray. If he gets in he will be our foreign minister - do we want someone like him fronting us on the world stage?"
TVNZ spokeswoman Megan Richards said that the incident was "clearly a joke" and any further issues should be addressed through the Broadcasting Standards Authority.
"With Paul Henry, what you see is what you get," she said.