One New Zealand says a widespread internet outage this morning was caused by one of its technology partners. 

Ninety cell towers were taken down by technical problems - leaving some customers in the South Island and lower North without service or internet.

The company says the outage began about 1:30 this morning and it took hours to be fully resolved. 

One NZ Chief Executive Jason Paris told Heather du Plessis-Allan that the issue was caused by a bug in one of their vendor's software.  

He says it tried to roll back the update it had made, but the bug didn't go away. 

The outage also affected 2 Degrees customers.

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