Animal welfare group Open Rescue went undercover at Colin Kay's farm over the weekend where they again filmed distressed and unhealthy animals.

MAF have previously investigated the farm and this latest footage has sparked a fresh investigation, which is raising questions over why nothing has changed.

Open Rescue gained access to the farm through an unlocked door and managed to gather enough evidence within the first 15 minutes of their visit.

One pig's ear was so badly infected it was raw and weeping. Another pig had an infected foot and one even had a prolapsed rectum.

Deirdre Sims from Open Rescue said she cannot believe the pigs have been found in this condition again.

"There is no excuse to keep animals confined and suffering in disgusting conditions like this.

"I just don't know what it is going to take to change this industry."

Hand Kreik from SAFE, a national animal rights organisation, agree something should have been done when this farm was first discovered.

"The real tragedy is that those pigs have been in those crates since Mike King saw them 15 months ago."

However he said that Kay's farming practices are currently legal.

"Don't forget the processes Colin uses on his farm are not illegal, so he could well pass an audit and he could well have his pork 'welfare approved' by the New Zealand Pork Board."

The claims were put to Kay by TVNZ's Close Up programme, who said the pigs were being treated for their injuries before the filming took place.

He said the pigs got their wounds from fighting and all 200 pigs had now been checked and cleared by a vet. One pig however had to be put down.

But Freshpork NZ Vet Selwyn Dobbinson said the injuries seen in the footage are not common at pig farms in New Zealand.

"In 20 years of practice it would be unusual to see two animals like that."

Fifteen months ago Open Rescue took high-profile pork ambassador Mike King to the same farm to show him the appalling conditions the pigs were being kept in.

Mr King was so shocked by what he saw he spoke out publically and subsequently parted ways with the Pork Board.

CEO of the Pork Board, Sam McCivor, said they have responded to the claims by beginning an audit of all farms throughout New Zealand.

"The commitment of the industry is by September 30 this year all pig farms will have been audited."

However because Mr McCivor's farm is yet to be audited he could not comment specifically on its performance.

But SAFE said this audit is a "smoke screen" for the 'welfare approved' label that the board is hoping to bring in.

"They are only doing an audit for one reason, they want to bring out a label reading 100 per cent welfare approved pork to give to farmers that meet their very, very low standards," said Mr Kreik.