Helen Clark's stunning revelation today that she was told in February by Owen Glenn that he had donated $100,000 to Winston Peters leaves the Prime Minister with a lot of explaining to do, says National Party Leader John Key.

"This is a stunning revelation.  Months have gone by since Helen Clark was informed by Mr Glenn about the $100,000 donation.

"The public was firstly told that Mr Peters had not received any money from Mr Glenn, then the public was told that Mr Peters had in fact received a donation but had not known about it, and then finally yesterday they were told that Mr Peters had personally solicited the donation.

"Today, we learnt that Helen Clark herself had the relevant information all that time.

"Helen Clark has got a lot of explaining to do today to the New Zealand public.

"The public are entitled to know why she withheld this crucial information for so long."