Three laptop computers were stolen after the National Party's headquarters in Epsom, Auckland were broken into overnight.
National finance spokesman Paul Goldsmith told 1 NEWS the burglary was "a disturbing and sinister start to an election year".
Mr Goldsmith said the thieves "forced open" a window and entered the property yesterday, but the exact time is unknown.
"Office workers here at the National Party came in and found that a room had been broken into, the window latch had been broken, and three laptops had been stolen.
"It's a National Party office and it's National Party details on the laptops.
"Our great concern is that it is political motivation that somebody's come in and trying to access data in an illegal fashion."
He said the party was waiting on police to investigate the scene.
"A lot of New Zealanders suffer from crime and so those sorts of events happen. It's interesting, we've got to look at the details here, but what we've seen is only laptops been stolen. There are other things in the room that could've been stolen that weren't."
In a statement police said they "received a report of a burglary at an address on Great South Road, Epsom, about 9.45 this morning. Police will attend the scene today."