Collins' explanation at odds with Chinese firm's formal invitation, says Robertson.
Labour MP Grant Robertson says Judith Collins' claim that she dropped in to Oravida in Shanghai for a casual cup of tea does not ring true after a formal invitation from the company two weeks before the Justice Minister's trip was released in documents under the Official Information Act.
Mr Robertson has accused Ms Collins of a conflict of interest because her husband is a director of the milk exporting company and it put on its website a photo of her saying she had tasted and "endorsed" its milk.
Ms Collins has said she did not endorse the company's products and had made it clear in advance that it should not use her photo to promote itself.
Early last week, Ms Collins described the visit to Oravida in Shanghai as "a cup of tea on the way to the airport" and as a "20 minute cup of tea, with milk".