A Givealittle campaign has been launched to help the cameraman who's suing the Prime Minister for defamation over the 2011 Teapot Tape saga.

Bradley Ambrose is suing Prime Minister John Key for $1.25 million over comments made in which Key alleged Ambrose intentionally recorded a conversation between him and then-ACT Party leader John Banks.

Former journalist Greg Treadwell said the case will come at considerable cost to Ambrose, who's struggled to find work since the teapot saga.

Treadwell launched the campaign to ensure Ambrose gets his day in court, and to stand up for the rights of journalists.

"It is mostly about journalism and defending journalism at a time when the powerful in society are pushing back at the fourth estate role, and I do genuinely believe it's under serious threat," he said.

"Ambrose, as I understand it, found it very hard to find work since the Teapot Tapes saga. There were not charges against him brought by police, he's done nothing according to the law and yet he's got no work as a result and that's an example of the chilling effect."

Key's legal bills would be paid out of the taxpayer-funded parliamentary budget for the National leader's office.

The Prime Minister has previously stood by his statements about Ambrose.