The Labour Party says safety and environmental issues must be considered when oil exploration permits are granted and the Greens want a moratorium on applications until processes are put in place.
The Government did not consider the environment when awarding a petroleum exploration permit for an area off the North Island's East Cape, an official document shows.
The permit, New Zealand's first over the Raukumara Basin, went to international Brazilian-based company Petrobras and covers an area of more than 12,000sq km.
Its five-year permit will give the company time to do thorough explorations and assess whether there is potential to mine for oil or gas.
Documents obtained by Radio New Zealand under the Official Information Act show the decision to award the permit was made on technical and economic grounds and did not consider safety or environmental factors.
Petrobras was required to show it would use good oil field practices.
Energy and Resources Minister Gerry Brownlee said specific environmental requirements did not need to be considered until drilling began.
But Labour's environment spokesman Charles Chauvel said there was a major issue right now.
"We have seen in recent months with the Gulf of Mexico disaster the damage that can be done when things go wrong with offshore drilling," he said.
"It is madness, when the Government is looking at expanding this activity, not to have stringent environmental checks in place before these applications can be considered."
The Green's energy spokesman, Kennedy Graham, said it was disingenuous for Mr Brownlee to say he would consider the environment later when he had already issued a permit for Petrobras to drill an exploratory well.
"An exploratory well poses all the same risks of a production well and Petrobras already has a permit to drill if it wishes," Dr Graham said.
"If an exploratory well runs into trouble, has Minister Brownlee ensured that there is a relief well capability in place to respond, or do we have to wait six months for a foreign rig to arrive and a further four months for relief drilling while our fisheries and shorelines are destroyed?"
Environmental concerns were raised when the project was announced.
At the time Mr Brownlee said the Government and Petrobras were aware of environmental concerns - particularly soon after the Gulf of Mexico industrial accident and oil spill - but he was comfortable with the company's "sensitive" approach to its work and legislation was being worked on in terms of environmental requirements needed to be put in place in New Zealand's exclusive economic zone.
Since then the Government had announced a new environmental protection agency (EPA).
Environment Minister Nick Smith said the EPA would help protect New Zealand's ocean from catastrophes similar to the oil spill in the Gulf of Mexico.
"The Government is determined to ensure that New Zealand's marine environment is properly protected as we expand the petroleum exploration and development in the exclusive economic zone," he said.
