The Government is being accused of trying to hide a report that shows the homes of 130,000 New Zealanders are at risk from climate change.
The Ministry for the Environment report was delivered to the Government in April.
It found 133,000 people were at risk of "higher levels of coastal erosion", with homes in Canterbury, followed by Hawke's Bay, are most at risk from sea level rise.
The report warns sea levels could rise 30cm-40cm by 2050, with what is now a "rare storm" event happening every year.
Green Party leader James Shaw was leaked the report and says the Government's failure to release it earlier has affected the public's and businesses' ability to plan for rising seas. The current available Ministry for the Environment data is nearly 10 years old - from 2008.
"It seems that there are inconvenient truths in this new report, which the Government would rather not talk about in the lead-up to the election," says Mr Shaw.
"This 284-page document makes disturbing reading and National seems determined to hide it so it can continue to avoid real action to reduce climate pollution and real action to deal with its consequences, such as rising seas."
The Greens say Climate Change Minister Paula Bennett is sitting on a second report by a Climate Change Adaptation Technical Working Group.
"New Zealanders need the most up-to-date facts to be better prepared for the changes we're facing," Mr Shaw says.
The office for Ms Bennett told Newshub she has "received some early advice from the group.
"The draft final report is due in November and then the final report in March. The Minister fully intends to release the reports once the final one has been completed."