Parliament has unanimously called for action to prevent severe human rights abuses against Uyghur Muslims, in a motion that stopped short of calling those abuses genocide.
Speaking in the house after tabling the motion, the wording of which was changed just an hour beforehand, Van Velden said she had to dilute and soften the motion to gain the acceptance of the governing party.
"Our conscience requires that we support this motion, we know that a genocide is taking place ... genocide does not require a war, it does not need to be sudden, it can be slow and deliberate and that is what is happening here.
"Some people think it is brave for our Parliament to debate something the Chinese Communist Party may disagree with. Think about that for a moment, we are elected by the people of New Zealand to debate freely and fearlessly - just so long as we don't offend the Chinese Communist Party. That is what it would have meant to not have this debate."
She said the party's motion was not a criticism of the country of China or Chinese people, or of Chinese New Zealanders.
"The ACT Party believes it would be irresponsible not to ... can the CCP play us off as the weakest link in the Western alliance? We will abandon our longest ally across the ditch? ... our small country has more to lose than most in a world where democratic countries are bullied.
"We must make sure the standards of the world are set as high as possible."
She said there had been imposition of contraception and forced sterilisation on the Uyghur population, and noted the US had twice declared there was a genocide occurring, under President Trump and President Biden.
Foreign Minister Nanaia Mahuta acknowledged unanimous support for the motion across the house.
She said Prime Minister Jacinda Ardern had raised the concerns directly with the Chinese government, and had consistently called on China to respect the rights of the Uyghur people and other ethnic minorities.
She said the government had not formally designated the situation of genocide, but it was not due to lack of concern.
"Genocide is the gravest of international crimes and a formal legal determination should only be reached following a rigourous assessment on the basis of international law. International courts have required fully conclusive evidence before reaching a conclusion of genocide.
"New Zealand has not previously made an independent determination of genocide, we relied upon judicial findings of genocide in the case of Cambodia, Rwanda and of course the Holocaust."
National's Todd Muller said the ability to engage and discuss ideas and concerns, were critical to ongoing peace and prosperity, but the depth of the relationship with China meant a willingness to not always agree, to listen and where necessary be criticised.
"While analysts see trade in terms of billions of dollars and percentage of exports and the rise of e-commerce, the true strength of our commercial and cultural connection is anchored in the relationships between our people - Chinese and New Zealanders, Chinese New Zealanders, and their families back home."
"New Zealand is known for its willingness to walk softly on the hard paths of geopolitics, but we walk our own path, we walk in a manner that seeks to resolve and not to compound but we speak with our own voice. We speak it to those we believe should hear us but we do not seek to grandstand.
"But neither do we shirk from uncomfortable conversations and today this House speaks in one voice with our concerns about severe human rights abuses in China."
He said they understood that China viewed any matter relating to its people as entirely a matter for its own consideration, "but we share one planet".
Green MP Golriz Ghahraman called for a stronger wording of the motion, and criticised both major parties for bringing up trade.
"The Green Party unequivocally condemns the grave atrocities being suffered by the Uyghur minority in Xinjiang province and other cultural and linguistic minorities at the hands of the Chinese government."
She thanked Van Velden for bringing the motion and said she regretted the House had "shied away" from talking about "atrocity" crimes such as genocide.
"It isn't the crime of crimes, all atrocity crimes are equal before the law in international courts ... what matters is our actions and I was deeply disappointed to hear leadership from both major political parties refer to trade as a consideration for them when they were discussing whether or not they would allow a motion using the word genocide when they were talking about the mass torture, extrajudicial detention, sterilisation and slavery of some one million people."
"That was stunningly callous, it was absolutely morally indefensible and it is a breach of new Zealand's legal obligations."
She said New Zealand was the only country in the world that still bought slave labour goods from the region.
Te Pāti Māori MP Debbie Ngarewa-Packer said the party welcomed the Greens' motion to revise the wording.
"We will continue to advocate for indigenous peoples and fight racism and bigotry in all its forms. We stand in solidarity with all indigenous and oppressed peoples right around the world. Ethnic violence starts with racism. We should use this place to lead and stamp it out."
The Māori Party struggled to understand why ACT had suddenly developed a desire to support indigenous peoples in China, considering they were well known, she said, for pushing colonial agendas that oppressed indigenous people in Aotearoa, and had just five months ago called for the abolition of New Zealand's Human Rights Commission.