Prime Minister John Key is planning to spend the day in Dunedin tomorrow.

Details about his visit are being kept secret by his staff.

All they will reveal is he'll be spending the day in Dunedin, attending a number of events including a charity dinner.

They say the Prime Minister won't be talking to media, and all his scheduled visits are private.

It's not clear whether he'll be staying in the city tomorrow night.

The Prime Minister has recently been participating in global climate change talks in Paris.