One of the main internet cables into New Zealand that was damaged, and left many users with slow connections, has now been fixed.

International telecommunications company Vocus, which owns Slingshot, Orcon, and Flip, says a major fibre cut in Sydney was impacting internet connections to New Zealand and the US.

It says the damage was caused by a third party contractor performing civil works earlier this week.

Vocus says the cut caused slow connectivity to New Zealand and the United States.

Slingshot, Orcon, and Flip, issued alerts about 7.30pm to customers about the issue, saying two fibre cables had been broken.