Visitor numbers are up on the country's Great Walks. Photo Getty

Director-general of the Department of Conservation Lou Sanson says it may be time to start charging for the use of the country’s Great Walks.

Lou Sanson.

At a Queenstown Chamber of Commerce breakfast in the resort yesterday, Mr Sanson said while the Great Walks brand had "exploded", it was creating some problems.

A report prepared 18 months ago said 30% of international visitors came to New Zealand to connect with nature. That figure was now 50%. As tourism numbers increased in New Zealand, it was important to protect the country’s point of difference - its natural environment - he said.