A student had a knife held to his throat by a man who threatened to cut off his fingers and kill him if he didn't give him $100 to buy P.

Police investigating the brutal sexual assault of a woman by four men in Tokoroa last weekend have not yet made any arrests.

Parts of the North Island are set for a soaking today, with up to 140mms of rain expected to fall in some areas.

Fonterra says it won't hesitate to take action, "including refusal to collect milk" if deliberate animal mistreatment is proven.

New Zealand's biggest privately held dairying operation allowed dozens of calves to slowly dehydrate to death.