The Diplomatic Protection Squad has blown out its budget by more than $1 million.
Figures obtained under the Official Information Act show the squad, which provides protection to dignitaries, spent about $5.2 million in the year to the end of June, $1.1 million over its budget.
The squad overspent by $800,000 in the 2009/10 financial year.
The Labour Party is blaming Prime Minister John Key for overusing the squad and maintaining a hefty and expensive entourage.
Labour's state services spokesperson, Chris Hipkins, says Mr Key has an unprecedented level of security that is two to three times the level of his predecessor, Helen Clark.
However, Justice Minister Judith Collins says the squad had an unusually busy year due to the Rugby World Cup and the election.
Ms Collins told Radio New Zealand's Summer Report programme the squad protected visiting dignitaries during the Rugby World Cup and members of opposition parties during the 2011 election.
The minister would not say where in the police budget the extra money came from, or whether the Government had provided additional funding to the police.
Police say spending is up because of rising travel and accommodation costs.