Votes cast by New Zealand-based Britons for the British election may not have been counted due to the disruption to air travel in Europe caused by volcanic ash from Iceland.
Voters were advised to send their postal votes early because the ash might have prevented them from arriving for the deadline on 27 March.
The High Commission in Wellington also recommended Britons to make a proxy vote, where a family member or friend in Britain casts the ballot on the voters behalf.
Unlike in New Zealand, postal votes for the British election are not counted after polling day.
There could be up to 49,000 people in New Zealand who were eligible to vote.