Prime Minister John Key will leave on a charm offensive of Latin America next week in the first bilateral visit of the region by a Prime Minister since Helen Clark in 2001.

Twice in the past decade, Solid Energy has enjoyed revenue close to $1 billion, and aside from last year has returned some healthy profits - and dividends for the Government.

Testing for a toxic agricultural substance in New Zealand dairy products has found no traces of it after mid-November last year.

The exchange rate is too high, Reserve Bank governor Graeme Wheeler says, but there are no simple solutions available to the bank to lower it.

The hot dry summer in the North Island is helping to push world dairy prices up - but the high kiwi dollar is taking the cream off the top.

In the fifth straight gain, prices in the latest world dairy auction rose 3.1 per cent overnight, takings prices to their highest level in five months.

New Zealand has become the second country in the world to approve plain cigarette packets.

The Government is expecting legal challenges over plain cigarette packaging and has warned they could cost taxpayers up to $6 million.

Prime Minister John Key says he is expecting legal challenges if the Government goes ahead with a plan to introduce plain packaging for cigarettes.

The Reserve Bank is grappling with the prospect of a property bubble emerging from the current low interest rate environment.

The NZ dollar has risen above 85 US cents for the first time since September 2011 amid expectations retail sales figures today will add to a string of strong data.

I visited China for a research project on the ivory trade in January. It took two years of groundwork first.