Spark is working to fix a fault which has cut broadband to customers in Queenstown, Wanaka, Arrowtown and Cromwell.
Spark communications adviser Cassie Arauzo said technicians were on site at the fibre line investigating where today's suspected cut was and what caused it.
"Once we identify the location of the issue we will be able to assess the physical work required to reach the fibre line and repair it. Until then we can't put an estimated time on when it will be fixed.
"We apologise for any inconvenience and we would like to assure customers that our technicians are working hard to get it fixed as soon as possible."
It was unclear how many customers were affected.
