Prime Minister: Twitter full of 'trolls and bottom feeders'

Twitter sure can be a challenge of politicians, but New Zealand's Prime Minister has some words of advice: post, don't follow.

After one of his Cabinet Ministers, Judith Collins, agreed to take time out after succumbing to social media stress, Prime Minister John Key gave his forthright views on the platform and its users, saying it was full of "trolls and bottom feeders".

In addition to taking a couple of days off, Collins has quit Twitter entirely - with the PM's backing.

"She's said to me I'm going to stay off," Key told Stuff.co.nz.

"My view is there's a lot of trolls and bottom-feeders on that and in the end they get in people's head. It's an anonymous situation, it's a form of cyber bullying, I don't engage in that."

While he posts on Twitter himself, Key said he did not follow feeds and he advised other politicians to do likewise.

"There's going to be a lot of bad stuff written out there on social media ... .that's just the nature of the job, it happens on all sides to all politicians but I don't see how any good can come from that stuff," he said.

Collins has been under pressure for her involvement in a meeting in China with a dairy company of which her husband is a director. She is expected to be grilled in Parliament today on the issue.

However, after another Cabinet colleague was forced to resign over the weekend she also appeared to attack journalists in the press gallery, challenging them to hold themselves to account for their own ethics.

She later apologised. 

Collins said Twitter was not a good space to be.

"It is actually a forum where people can be very abusive towards me and I'm just not doing it," she said.

Key said social media had been a big factor in Collins' problems.