Labour is accusing Justice Minister Judith Collins of corruption.
Ms Collins has been under fire for visiting New Zealand milk export company Oravida when she was in China last year. Her husband is a director on its board.
It has been revealed that Oravida received assistance from the New Zealand Government in dealing with the fallout from the Fonterra botulism scare last year, after it wrote to the Trade and Primary Industry Ministers asking for help.
Ms Collins said the matter was not discussed during her dinner in Beijing with Oravida executives and a border official.
She said the first she heard of letters requesting help was on Wednesday and she had not received them or read them.
Labour MP Grant Robertson said he does not believe Ms Collins - and in other countries what happened is called corruption.