Morning Report presenter Sean Plunket has lost his Employment Relations Authority bid against his employer, Radio New Zealand (RNZ).

Plunket took RNZ to the authority after it refused him permission to write a column in Metro magazine, or to moderate televised political debates for TVNZ and TVNZ7.

He maintained RNZ was in breach of the Bill of Rights Act in preventing him undertaking outside opportunities.

RNZ was purporting to control his spare time, and curtailing his fundamental freedoms, he said.

But in a decision released today, authority member Denis Asher found RNZ had the right to decide if Plunket's activities could be deemed an "actual or potential" conflict of interest.

If RNZ did consider that the case, it had the right under its employment contracts and editorial policies to decide the best course of action, the authority said.

RNZ had agreed to a number of secondary employment activities by Plunket, it said. Plunket had been told he was free to write a column for Metro, provided it was not a political column.

There was no evidence Plunket had been singled out for "disparate or unfair or unreasonable treatment", the authority said.

RNZ reasons for declining Plunket's wish to appear on TVNZ and write for Metro were "on their face, coherent and objective", the authority found.

RNZ had met its statutory and contractural obligations, it said.

Plunket was still free to exercise his freedom of expression in his spare time, other than by way of paid secondary employment where conflicts of interest might exist.

"Freedom of expression is not to be conflated or confused with secondary employment potential derived from the party's Morning Report status."

In the Wellington hearing last month, RNZ chief executive Peter Cavanagh said a political column could lessen Plunket's perceived objectivity as a Morning Report host.

Hosting a TVNZ7 debate on internet policy and copyright issues during election coverage could have confused viewers, and RNZ needed "all hands on deck" for their own election coverage, Mr Cavanagh said.

Plunket told the authority Mr Cavanagh had told him he was part of the broadcaster's "brand", as though "anything I said or did anywhere would reflect on Radio New Zealand".

He said Mr Cavanagh later told him "you might find the offers stop coming if you don't have the profile of Morning Report" and "if you don't like it, get another job".

He found Mr Cavanagh "menacing" and was distressed at the idea he may lose his job.

Mr Cavanagh told the authority that "perhaps out of frustration, I may have reminded him there are other employers out there".

He said Plunket and RNZ's names were "joined at the hip", but he did not recall referring to him as part of RNZ's brand.