Waihi Beach has been closed after containers and debris from the stricken cargo ship Rena washed ashore and reports of people stealing the washed-up cargo.
Waihi Beach Community Board member Derek Mills said there were four containers on the beach and at least another three could be seen floating out at sea.
"There's a least four containers on the beach and one of them is broken up and there's something that looks like milk powder.
"There's a great heap of that on the beach," he said.
Police spokesman Andrew McAlley said the beach had been closed for public health reasons.
"In addition to that we have had confirmed reports of people removing stuff we believe to be milk powder from one of the washed-up containers.
"It's being treated as theft but our priority is public health and safety so at this point in time we urge people that have taken stuff to return it to the public accessways to the beach where it can be decontaminated. Property from in the containers remains the property of the container owners and insurers.''
Mr Mills said he confronted one person who stole a bag of washed-up cargo.
"I did speak to one gentleman who'd picked up a bag of whatever it was and putting it in his van and when I told him that was not to be done he just said `have a life mate, it's only milk powder' and shoved it in his boot and drove off,'' he was quoted as saying by NewtalkZb.
Waihi Leader editor Fritha Tagg was at the scene this morning.
"The beach is littered with polystyrene and there are lots of people on the beach looking," she said. "It runs from about the middle of the beach north."
Further along the beach there were "hundreds and hundreds of bags" of milk powder strewn into large piles.
"You can actually smell the milk powder but it is still powder, the bags must be well sealed."
Ms Tagg said she could see another container in the ocean that appeared to have milk powder inside.
Meanwhile, Maketu and Eastern Bay residents are waiting to see if any debris or oil from the Rena also washes up on their beaches.
While the exact path of the debris and oil is not yet known, Maketu locals hope they are not in for another big clean-up.
Thornton Beach maritime expert George Johnston said existing sea currents would send debris to Maketu, which was badly hit by oil when the Rena grounded off the coast in October.
"Over the years everything, from wrecked boats to bodies, either ends up near Motiti or further down the East Coast.
"If anything in the water heads toward the East Coast, it generally passes between Whale and White islands and keeps going down.''
Bay of Plenty Regional Council community relations manager Bronwyn Campbell said the containers and cargo in the water were currently going north but a wind change was expected, although that alone would not determine where they went.
A cautionary area around the Rena includes from Waihi Beach to Mayor Island to Maketu and boaties are urged to navigate with extreme caution, travel at slow speeds, keep a good lookout and to stay off the water at night.
Ms Campbell said the debris field was extensive and its movement was unpredictable and could extend further.
Maritime New Zealand said another seven containers were known to be within a mile of the Waihi shore, and container recovery company Braemar Howells was using tug boats to tow them.
Teams were already on Waihi Beach to secure and start removing the debris, with another investigating unconfirmed reports of a container ashore just inside the Bowentown entrance.
