Armed police are guarding several entrances to at least one inner city Auckland building after threats were reported.

Police said the threats came from South Auckland and the armed police had been posted as a precautionary measure, although few other details were known.

Police were at a building in Durham Lane where at least two or three entrances were being guarded, said police spokeswoman Noreen Hegarty.

She said the threats were reported to the police second-hand and the police action was precautionary.