The Green Party says Prime Minister John Key should talk to China's leaders at APEC about the jailing of a man who pushed for compensation for victims of the Sanlu milk poisoning scandal.
At least six babies died and 50,000 were hospitalized by baby milk formula that was deliberately contaminated with melamine in 2008.
The milk powder was produced by a partner of Fonterra's, Sanlu.
Zhao Lianhai has been jailed for two-and-a-half years - having already spent a year in detention - for "inciting social disorder" in trying to get compensation for the victims.
Green Party human rights spokesperson Keith Locke says Mr Key should tell China's leaders the jailing is unacceptable.
Mr Locke says Mr Key has a golden opportunity to tell China's leaders, whom he will meet at the APEC meeting in Japan.
Human rights group Amnesty International is also calling on the Government to condemn the prison sentence.
It says Mr Zhao's only crime was to set up a website to provide information for parents of children affected.
Chief executive Patrick Holmes says the Government and Fonterra have a moral duty to say something to China.
Mr Zhao's lawyer says the crimes he was accused of were nothing more than what ordinary citizens would do to defend their rights.
His wife says the sentence is unacceptable and will appeal against it.