Opponents of the trade have long argued that Morocco runs an illegal military occupation of phosphate-rich Western Sahara.
And, as a result, New Zealand should not be buying products from there.
A four member Moroccan team has been holding a series of meetings here, arguing the incorporation of Western Sahara into Morocco is a benign process that actually helps the territory.
New Zealand saturates its fields with phosphate annually, because intensive agriculture sucks it out of the ground.
Phosphate is vital for plant cell metalolism.
That means every top dressing pilot spreading fertiliser on a New Zealand farm has a link with Western Sahara.
Seventy percent of all New Zealand’s phosphate comes from there, and one fifth of Western Saharan output goes to New Zealand.
As a result, Western Sahara is not just another intractable foreign dispute — New Zealand and Morocco have been locked together in a trading embrace for 30 years.
The vice president and general counsel for the state phosphate giant OCP, Otmane Bennani Smires, said he wanted it to stay that way.
This trade has progressed quietly for years but was thrown into the limelight when a ship carrying phosphate bound for New Zealand was detained in South Africa.
A court found the phosphate did not legally belong to the Moroccan company because Morocco’s occupation of Western Sahara was illegal.
Mr Smires insists Morocco’s occupation is benign.
“We have a programme that brings wealth and development to the local population,” he said.
“We are very proud to employ 2500 people, 76 percent from the local community.”
But this view is contested.
Mike Barton campaigns for the Western Sahara in New Zealand and he said the people of Western Sahara see little benefit from Moroccan occupation.
“The bulk of the Western Saharan people live across the border in refugee camps, as they have for 40 years, and they do not see any benefit from the exploitation of their own resources,” he said.
Western Sahara is a piece of desert land of a similar size to New Zealand.
It was a Spanish colony but was taken over by Morocco in 1975.
This was repeatedly condemned by the United Nations and the New Zealand Ministry of Foreign Affairs and Trade wants what it calls ‘genuine self determination’ for the people who live there.
But there are no sanctions against Morocco, and Mark Wynne, whose company Ballance Agri Nutrients is a major purchaser, said he planned to go on buying.
“There is only one enduring solution for this problem and this is for it to get resolved by the United Nations, and that has been our position from day one.”
Meanwhile the Ballance-ordered shipment of phosphate that was seized in South Africa is awaiting a court-sanctioned sale through sealed bids on 19 April