There is a very real conflict of interest for the cabinet minister whose brother is facing serious assault charges, Labour Party leader Andrew Little has said.
Mr Little said he believed the Prime Minister should have acted sooner, after being told of the charges more than a month ago.
At yesterday's post-Cabinet news conference, John Key was reluctant to discuss criticism of his decision not to stand the minister down.
Mr Little - who said he knew which minister was involved - said the issue is not about what the minister's brother is alleged to have done, but how the minister's role could be compromised by the situation.
Mr Key yesterday said there was no conflict of interest and advice he had received made it clear ministers were not accountable and should not have to stand down over the conduct of members of their families.
"A minister shouldn't actually just step down because one of their family members has an issue that they're dealing with, providing that there wasn't a conflict prior to that point and any potential conflicts are managed," he said.
The minister's brother is reported to be due to appear in court today.