New Zealand trade could be harmed if Britain leaves the EU, an agricultural economics professor says.
Lincoln University professor Alan Renwick said most of Britain's energy would be directed at its relationship with the EU, which could hurt its trade relationship with New Zealand.
The voting is due to start this afternoon and the results of the vote will be known tomorrow afternoon.
Mr Renwick, who moved here from Ireland last year, said Britain should remain part of the EU.
If Britain decided to step out on its own then there were several risks for New Zealand, he said.
"I think UK is quite a reforming force in Europe, particularly around agricultural policy and the common agricultural policy.
"So if the UK leaves, and they leave the Brussels table, then perhaps the more conservative forces fishing for more protection for agriculture may have a greater say, and clearly with our importance of trade and access then the removal of the UK could be a challenge for that.
"There's also an indirect effect... we've now got talks going ahead between the EU and New Zealand for freer trade, again very important for us.
"But if Britain leaves then it's likely a lot of activity and a lot of energy in the EU will be about the relationship on the EU, and the UK and New Zealand is going to be pushed down the pecking order and that could be detrimental to our trade."
New Zealand had worked hard over the years to get to where it was, he said.
"New Zealand hasn't been sitting on its hands for 40 years waiting for the UK to come back, they've developed strong trading relationships with Asia, so in that way it's not so important.
"But there are New Zealand companies based in the UK and they will have to decide whether to stay there and get another base in Europe or to move to European countries, so that might be important."