Port of Tauranga operations haven't been disrupted yet by the potential shipping hazard of up to 300 containers washed overboard when the Rena split in two, says chief executive Mark Cairns.

Port channels are being checked to ensure no risk is posed to arriving and departing vessels. So far 21 containers have been tagged and buoyed out of a total 40 spotted in the water, with the priority being to avoid them beaching, according to Maritime New Zealand's latest media release.

"A lot of our own resources, such as sonar, are being used to make sure port channels are clear" Cairns told BusinessDesk.

A number of the containers will be submerged, posing a risk to pleasure boaters who may not be aware of the hidden threat, he said.


Michele Poole, a spokeswoman for Maritime New Zealand says the containers are believed to contain milk powder, timber, plastics and furniture.

Containers have washed ashore at Waihi beach, which has since been closed by police to prevent looting, Fairfax reported.

Maritime New Zealand is scheduled to give an update at a media conference at 3pm.

Shares of Port of Tauranga fell 0.4 per cent to $10.08 on the NZX today, having reached a record high $10.20 last week on news that Fonterra Cooperative Group has joined container line Maersk in moving its business from Ports of Auckland, where operations are being disrupted by strikes.

The Rena had 1368 containers aboard when it became initially grounded, with 89 previously lost overboard and 282 removed since the recovery began on November 18.