The chasm highlighted division in the UK's Conservative Party and uncertainty around the outcome of the vote.
"While Cameron will be campaigning for the UK to stay in the EU, a quarter of his Cabinet will be voting the opposite and polls are evenly divided," Bank of New Zealand currency strategist Jason Wong said in a note. "Implied volatility on GBP has recently moved up to its highest in five years, signalling increased currency volatility ahead as the referendum nears."
In New Zealand today, credit card spending data for January is released at 3pm.
The New Zealand dollar slipped to 92.84 Australian cents from 93.12 cents on Friday ahead of a speech by Reserve Bank of Australian assistant governor (financial markets) Guy Debelle on interest rate benchmarks.
The kiwi edged up to 59.59 euro cents from 59.48 cents on Friday, and gained to 4.3255 yuan from 4.3135 yuan. It slipped to 74.55 yen from 74.67 yen. The trade-weighted index advanced to 72.21 from 72.07 on Friday.