Labour is going to the Ombudsman in an attempt to force the Treasury to immediately release documents it holds on the government's investment in a Saudi Arabian farm.
Trade spokesman David Parker says ministers have dodged questions and he can't get documents under the Official Information Act.
"There's been an orchestrated delay from the Ministry of Foreign Affairs and Trade, the Ministry for Primary Industries, Trade and Enterprise, and now the Treasury," he said on Friday.
Mr Parker says the Treasury has listed the relevant documents and told him it will put them up on its website early next month.
"The Treasury has the information and it is obliged to release it now," he said.
"Labour will lodge a complaint with the Ombudsman."
Mr Parker wants details of the $11.4 million the government invested in Hmood Al Ali Al Khalaf's Saudi Arabian farm.
The businessman lost millions when the export of live sheep for slaughter was banned in 2007 and the government has confirmed diplomatic relations with Saudi Arabia were "poisoned" as a result.
Saudi Arabia put a free trade agreement on hold, and it still hasn't been signed.
The government says the money was used to set up an agricultural hub on Mr Khalaf's farm to showcase New Zealand equipment.
Part of it was a $4m "facilitation payment" to Mr Khalaf and Labour wants to know exactly what it was for.
Mr Parker believes it was to secure the free trade agreement - a practice he says is illegal in other countries.