The New Zealand dollar slipped as the US dollar strengthened after Federal Reserve officials signalled the US central bank is on track for a potential rate hike next month.
The kiwi was at 64.65 US cents at 8am in Wellington, from 64.53 cents at the New York close and 64.73 cents at 5pm last Friday.
The trade-weighted index was at 70.09 from 69.98 on Friday.
The US dollar index, which measures the greenback against a basket of currencies, touched its highest level in eight days after Fed vice chair Stanley Fischer told a central bankers conference at Jackson Hole, Wyoming, at the weekend that the Fed remained on track for lift-off this year and that the "door remains open" to a September hike.
The comments add to those from Fed Atlanta president Dennis Lockhart that the odds of a rate hike in September are roughly even, and from St Louis Fed president James Bullard and Cleveland Fed president Loretta Mester playing down the impact of recent market turmoil.