Prime Minister John Key only talked briefly about the decision by two agencies to cut New Zealand's credit rating as he hosted a series of celebrity guests in an hour-long radio show this afternoon.

All Blacks captain Richie McCaw and film director Peter Jackson were among those interviewed as Mr Key fronted the Prime Minister's Hour on Radio Live from 2pm, just as Standard & Poor's joined Fitch Ratings in downgrading the country's rating.

He told listeners the hour was an "election free zone", but offered to "talk to someone important" about Coronation Street being moved to an earlier timeslot.

It wasn't until the latter half of the show, under prompting from Radio Live host Paul Henry, that Mr Key made reference to the Standard and Poors downgrade.


He blamed it on high private sector debt and a "very jumpy" atmosphere at major rating companies.

He was disappointed at S&P's decision. "But hey, it's private sector debt".

A spokeswoman for Mr Key said Radio Live had stipulated Mr Key's hour must be free of politics.

The station had obtained advice from the Electoral Commission that political content could breach election rules in the regulated period.

Immediately after his stint, Mr Key had spoken to reporters outside for almost 20 minutes, largely about the credit downgrades.