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 covered an area of more than 12,000 square kilometres.

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 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.

Environmental concerns were raised when the project was announced.

At the time 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.