New Zealand First leader Winston Peters has appealed a High Court decision to dismiss his latest defamation case against Television New Zealand (TVNZ).

Mr Peters previously alleged National MP David Carter made defamatory statements about him when chairman of a parliamentary select committee inquiry into the scampi industry.

He sought to sue TVNZ for broadcasting Mr Carter's comments but the case was struck out.

Mr Peters' lawyer, Brian Henry, told the Court of Appeal in Wellington today the case now concerned allegations broadcast on the network's Holmes programme in 2004.

The allegations were made in a sworn affidavit read to Parliament by Ken Shirley, who was then an Act MP.

Comments made in the House are subject to parliamentary privilege and are therefore exempt from certain laws such as defamation.

Mr Henry said the allegations were effectively repeated when Holmes featured clips of Mr Shirley reading the affidavit, closely followed by its author, Yvonne Dossetter, saying she stood by her statement.

"It's about the allegations made by her when she has no privilege," he said.

"TVNZ are liable for re-broadcasting."

Mr Shirley also told the show the allegations were "incredibly serious" and needed to be dealt with.

TVNZ lawyer William Akel said Ms Dossetter's comments could not be viewed in isolation.

"You can't rely on just one part in isolation, you have to look at the whole programme," he said.

"The media have got to be able to pick it up and give context to it."

The Court of Appeal reserved its decision.