"If the process is starting to unwind, then in the long run that is going to suit New Zealand and other commodity currency countries" because it signals the US economy is in better shape and it sparks a structural rerating of the New Zealand dollar, English said.
The recent decline in the New Zealand currency "is mainly Fed driven," English said. "Our Reserve Bank has limited capacity to intervene. It was referred to as a peashooter in a war zone."
English said there were a narrow range of circumstances where Reserve Bank governor Graeme Wheeler could intervene in the currency which appeared to have been "reasonably effective".
"Our concern is to ensure that there aren't big risks taken with the public balance sheet," he said.
The Reserve Bank sold a net $256 million into foreign exchange markets in April, its first intervention since 2007, and governor Graeme Wheeler has said he is willing to make further attempts to weaken the currency.
The bank reduced its foreign currency intervention capacity to $8.48 billion in April from $8.7 billion a month earlier, Reserve Bank figures show.