Surprise about scathing bullying allegations from a back-bench Labour MP.

Gaurav Sharma has hit out at bullying between MPs and from parties towards MPs..

He says it's facilitated and promoted by the Prime Minister's Office, the Parliamentary Service, party leaders' offices and party whips' offices.

Newstalk ZB Deputy Political Editor Jason Walls told Kate Hawkesby it's rare to see an MP break ranks like this.

He says for an MP to call out their party in such a public way is extraordinary.

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