Asked whether the fact that it appeared either Oravida or the Chinese official paid for dinner added to perceptions of a conflict of interest, Ms Collins, said: "actually it doesn't," before walking away from reporters.
The fact Ms Collins walked away from questions about the dinner was "not a good look at all", Labour Leader David Cunliffe said.
"She should come clean. Who paid for the dinner? Who was the Chinese official? Why did the ambassador not attend? Those are what New Zealanders want to know... they want to know how deep the conflict of interest goes.
"This is a minister who is on the run. Ministers who are on the run can't stay running forever and there's much more to come out on the Collins story. Labour is aware of other matters which will be brought to the public attention in due course."
Asked whether Ms Collins should find out who paid for the dinner, Deputy Prime Minister Bill English said: "You'd have to talk to Ms Collins about that".
"Clearly there's been a bit of interest in the dinner and I'm sure there's an answer there somewhere. It's up to her, she knows the relationships and what would be regarded as hospitable and polite."
Mr English said politicians often attended dinners or other meals where they didn't pay for their food and entertainment.
Despite Mr Key saying last week that he was "disappointed" that Ms Collins had told him and the media of the dinner sooner, Mr English said: "She's been quite transparent on the issue over the last few weeks".
"This is a competent minister who's laid out all of her involvement."