The Auckland offices of Unite Union have been burgled, with expensive electronics and a credit card stolen.

Unite's national director Mike Treen says it's the second time the office in Kingsland has been burgled, and comes after receiving significant political and media attention.

"They smashed their way into every office and went through filing cabinets. They went through boxes quite systematically, and unfortunately we lost quite a bit of quite important equipment."

Unite was involved in high profile protests on Wednesday against zero hours contracts, in particularly targeting McDonalds.

The burglary took place that same evening.