The risk to Te Aroha from the possible bursting of a tailings dam on the mountain above it should be eliminated by 2013 under a deal between the National Government and the Green Party.

Environment Minister Nick Smith yesterday announced a further $9.9 million towards the $16.2 million clean-up for the Tui Mine, deemed New Zealand's worst contaminated site.

He said a moderate earthquake or severe storm could damage the dam and involve loss of life and damage of up to $168 million.

"It is simply unacceptable to leave this dangerous tailings dam precariously sitting above ... Te Aroha. A moderate earthquake or a weather bomb could trigger the collapse of 160,000 tonnes of toxic material any day," he said at a joint press conference with Coromandel-based Green MP Catherine Delahunty.

The project would build on work already done at the mine, and he expected good progress.

"My hope would be that by July 2013 the risk of that tailings dam coming down the mountain and causing damage will be gone."

In addition to the work around the mine, the plan outlined strategies to prevent further contamination, as well as tackle other polluted sites. A register of priority sites will be established.

Dr Smith said there were estimated to be 20,000 contaminated sites in New Zealand, including former gasworks, timber and agriculture sites.

"The real nightmare for New Zealand is about those earlier sites. The truth is many of the companies have long gone."

The review would look at whether the parties involved in the clean-up could claim from a previous company that was responsible for the pollution.

Catherine Delahunty said the plan would give the public access to the national register to see where the pollution was.

- additional reporting by NZPA