Sir John Key is concerned about the global economy entering into dangerous waters again.

The former Prime Minister's now in the thick of business, as the chair ANZ's board and a director of Air New Zealand.

He told Mike Hosking a few local and global factors are causing concern for economists and bringing back thoughts of the financial crisis a decade ago.

"These fears include two major economies falling into worse positions, the US running big budget deficits, and China's massive year-on-year growth starting to slow."

LISTEN ABOVE AS SIR JOHN KEY SPEAKS TO MIKE HOSKING