New information on the Saudi sheep deal has led to more accusations of the Government picking favourites in its business deals.

Documents show Brownrigg Agriculture provided advice on the business case for the agrihub in Saudi Arabia and was then given the contract to build the demonstration farm.

Labour's trade spokesperson David Parker said it shows more serious wrongdoing by Foreign Minister Murray McCully, with a worrying pattern emerging.

"I think this is so basic, it's hard to think that this is all innocent," Mr Parker said. 

"It's a bit like the Sky City deal where someone got insider running, so the Government didn't follow its own rules, gave an inside running to someone who even got to help write the terms of the contract that was for their benefit."

Labour leader Andrew Little is calling for Mr McCully to be stood down, arguing the move would recognise the seriousness of the allegations to a Government which hasn't handled the issue well.

"The Government's attempts to deal with it was to release 900 pages of information, which looked more like trying to put people off the scent. But actually what the papers revealed is cause for concern, which is now why the Auditor General is taking interest."

Andrew Little said when something's gone wrong with propriety or taxpayers money, it's a serious misjudgement to make.