UPDATED 3.48pm Corrections Minister Judith Collins has been accused of overstepping her bounds by dishing out orders to MPs who want to visit prisons.

Collins sent an email to other politicians, telling them to organise prison visits through a Private Secretary in her office.

Greens Criminal Justice spokesman David Clendon said MPs have a legal right to visit prisons, and notifying the Minister is a courtesy, and sometimes not possible when there's an urgent issue to investigate.

"I will not wait for the Minister's approval or discretion to exercise a right that is given to me as an MP in the legislation," he said.

Collins is adamant it's not about her keeping a watch on the activities of opposition MPs.

"It's not a matter of tabs. I seriously don't worry about whether or not they go and visits prisons. I welcome it, I encourage them." 

Clendon said that the allowance for MPs to visit jails is one of the few oversight mechanisms our prisons have.

"There is no transparency about what goes in there. We don't have an independent inspectorate. We know that a journalist recently took three years to get access to interview an inmate."

But Collins said the protocols are the same as a set issued in 2009.

"What we're trying to do is encourage visits to prisons but we also want to make sure that those visits are really good for the MPs and they get the best information they can."

Labour's Annette King said Ms Collins is up to her old tricks, and trying to take more control than she's entitled to.

"This was tried before. And I think it might have been with Judith was the Minister, attempts were made to stop Members of Parliament going to prisons."

"They are awful places to visit, and I had one in my electorate. It is not a place I'd go unless I had a reason to go. I think it's Judith wanting to get a little control back, having lost it for so long."

But Ms Collins said her opponent is completely wrong.

"Annette is delusional on that one. It's really clear that it worked really well. MPs don't have to use it, but if they can, it just makes it a better outcome for them."