WELLINGTON, June 9 (Reuters) - New Zealand's central bank is keeping a close watch on a range of external risks that could impact monetary policy, the deputy governor said.

"The world could potentially end up throwing quite a number of curve balls at us," Reserve Bank of New Zealand deputy governor John McDermott said.

McDermott, who spoke to Reuters soon after the RBNZ's decision to hold rates steady at 2.25 percent, said the central bank is keeping a close eye on the Federal Reserve and on when policy makers there will raise rates.

Other risks included "brexit" - Britain exiting the European Union - which could cause volatility in financial markets, he said.

McDermott also signaled out a slowdown in China's economy and potential imbalances building up in the financial system there as significant concerns.

"We are watching China on two fronts, and we would classify it as a significant risk" to New Zealand's economic outlook, he said.

(Reporting by Rebecca Howard; Editing by Shri Navaratnam)