Claims by journalist Glenn Greenwald that the Southern Cross undersea cables have been tapped into or accessed are "total nonsense", according to a damning response by CEO Anthony Briscoe.

The cables, which link New Zealand to Australia, the Pacific and the United States, are untouched, Briscoe claims.

“I can tell you quite categorically there is no facility by the NSA, the GCSB or anyone else on the Southern Cross cable network," he adds.

“Let’s be quite blunt. To do this, we would have to take the cable out of service and I can assure you there’s no way we are going to do that.

“It is a physical impossibility to do it without us knowing.

"There is just no way it can be done. I can give you absolute assurances from Southern Cross – and me as a Kiwi – that there are no sites anywhere on the Southern Cross network that have to do with interception or anything else the NSA or GCSB might want to do.”

Briscoe adds that any breach of the cable would require temporarily shutting down its transmission for hours, adding that Southern Cross has monitoring systems built into its computers watching for any such break and they would be triggered as soon as any attempt was made.

“There isn’t a technology in the world, as far as I am aware, that can splice into an undersea fibre optic cable without causing a serious outage and sending alarms back to our network operation centre, that something’s wrong," he adds.

Briscose says Southern Cross is obligated to comply with the well-established and public lawful surveillance requirements in the Communications Assistance for Law Enforcement Act and related laws in the United States.

However there is no equipment installed in the New Zealand or United States landing stations, or on the cable itself, which could result in mass interception of communications.

"We are very disturbed that such unfounded allegations have been made and feel that it’s important for all New Zealanders to understand that this outrageous claim is totally untrue," he adds.