The founder of Kathmandu has pledged $2 million to fight animal cruelty - and will give cash to anyone who dobs in farmers' cruel practices.

Jan Cameron hopes "rewards" of up to $30,000 will entice insiders to expose any cruelty at battery hen and pig farms.

Estimated to have a personal fortune worth about $400 million, Ms Cameron hopes the money will put an end to sow crates.

Forty per cent of farms in New Zealand still use the small metal-barred crates. In an interview on TVNZ's Sunday programme last night, Ms Cameron said she would do "whatever it takes" to put an end to sow crates. "It's just torturing the animals."

She would reward anyone who provided information about animal cruelty at battery hen and pig farms.

"The maximum reward will be up to $30,000 depending what the legal or animal welfare outcomes can be achieved as a result of the information they bring forward," she said.

The money was there in case the informants lost their jobs.

Some money will also be given to the animal rights activist group SAFE, including for advertising to increase awareness of the situation.

"The most powerful people in this process are the consumers and they can decide," Ms Cameron said.

The "clean, green image" that New Zealand identified itself with was at odds with the torturing of animals happening behind farm doors.

Last year, comedian Mike King, the then face of advertising for New Zealand Pork, joined a break-in at a North Island intensive pig farm to help expose crate-farming practices.

SAFE activist Hans Kriek hopes New Zealand will follow Tasmania's lead of phasing out the crates by 2017.

"I think the feeling is if one country moves, the other can't be left behind."

Pork Board CEO Sam McIvor told Sunday he did not think sow crates were cruel and said the science behind them was being ignored.

"Pig farmers, at the end of the day, farm pigs because they like pigs. It's well proven that the use of sow stalls can be beneficial in early pregnancy."