Labour's Environment spokeswoman Maryan Street says planned reforms of the Resource Management Act (RMA) were a "smokescreen'' designed to conceal the real dangers of the Act.
Prime Minister John Key announced changes to the Act at a National Part conference this morning and said they will improve housing affordability.
The law changes will require local councils to provide a minimum of 10 years of urban land supply to cope with projected population growth.
It will also allow subdivisions to be non-notified unless they are clearly not the type of developments anticipated by the relevant plan and zoning.
Another change would limit the time for processing simple consent applications such as adding a deck or verandah from 20 working days to 10 working days.
But Ms Street said the vast majority of consents were already processed within the statutory 20 days.
"There has never been any substantial evidence for reform on this basis.''
The changes were a tragedy for New Zealand's "already compromised environment,'' Ms Street said.
"We need a firmer commitment to environmental protection these days, not a weaker one.
"The real danger is that the RMA is being turned into an Economic Development Act and environmental protections are being sacrificed in the process,'' she said.
The Green's also hit out at the reforms, saying the changes attacked the heart of the RMA.
"At present New Zealand is under the microscope from all our trading partners who are concerned that our clean, green image is a mirage,'' Green Party environment spokeswoman Eugenie Sage said.
"The changes would effectively throw out more than 20 years of case law about how the RMA should be interpreted.''
The RMA would become an "economic development act at the expense of our environment and local democracy'' under the changes, Ms Sage said.
Despite this, Business NZ have applauded the reforms.
Chief executive Phil O'Reilly said they addressed many of the problems with the RMA which had held back development, restricted new housing and contributed to New Zealanders being poorer.
"These planning changes will make a great difference to the average New Zealander seeking to own or develop a home or business, while at the same time continuing to safeguard our shared physical environment.''
"But such changes don't fully address the Act's unnecessary regulation of private rights in the name of the public interest, he said.
"There should be provision for compensation if people are restricted from developing their own land where there is no harm to others or to the environment,'' Mr O'Reilly said.
Speaking at the party's annual conference in Nelson, Mr Key said the reforms would address the heart of the housing affordability problem in New Zealand, by freeing up land supply and making it easier to build, extend and renovate houses.
"We want to see more houses built for families and more jobs for builders and carpenters; not bureaucrats checking passports at the doors of open homes as Labour would have us do."
Labour proposes to prevent house sales to non-residents unless they live in New Zealand or plan to build new homes, and they would be required to sell them once they left New Zealand.
Environment Minister Amy Adams told the conference she knew of a $3500 consent for a $800 job to remove a chimney and a $7000 consent for a four metre extension to a deck.
Mr Key said political opponents would paint National as anti-environment, but he dismissed these criticisms as "nonsense".
He said balance and pragmatism ran through the Government's decision-making, marked by the ''sensible" decision by Conservation Minister Nick Smith to turn down the bus tunnel to Milford Sound and the work of managing water resources through such bodies as the Land and Water Forum.