Oil protest target Petrobras says it values the right of protesters to express their views.

The Brazilian oil giant said its work off East Cape complied with all New Zealand and international laws and survey work was "safe and simple".

Environmentalists aboard yachts are protesting against a seismic survey of the Raukumara Basin and yesterday reportedly contacted the ship doing the work, the 3-D Orient Explorer.

They are worried that if oil is discovered and the prospect developed there is a risk of a spill into deep water, contaminating marine life and the coastline.

Petrobras, one of the 10 biggest oil companies in the world, said it was in the first phase of the five-year prospecting project which involved seismic and geological studies to help measure the potential for gas or oil.

The exploration permit covers 12,333sq km where earlier government seismic data and modelling work showed the basin had geology capable of trapping hydrocarbons in commercial quantities. Water depths range from coastal to 3000m at its northern reaches.

Petrobras said under the terms of the permit, its preliminary work must be finished by May next year and it would then decide to do more study or surrender the licence.

"We are committed to carrying our actions out in an integrated manner, valuing human and cultural diversity and promoting citizenship and respect for human rights, which includes the rights of the protesters to express their views," the company said.

The Petroleum Exploration and Production Association of NZ said the worst-case scenario for the industry would be for Petrobras to pack up and go home.

There was a risk of Petrobras thinking it was "all too hard," said the association's executive officer, John Pfahlert.

He warned protesters to be careful in the survey area as the survey vessel was operating a long way from shore and it posed real risks to protesters if they attempted to disrupt it operating.

The 3D Orient Explorer was 85m, weighed 3500 tonnes and the seismic gear it was towing extended 10km behind it.

"Protest vessels need to stay a healthy distance to ensure the safety of their vessels and crews and the crew of the 3D Orient Explorer," said Pfahlert.

Rules covering offshore exploration are under review.

Pfahlert said the industry was prepared to work with the Government to to address protesters' concerns regarding consultation and environmental laws for assessment.

"It's up to the Government to make progress on fixing this issue. Industry is ready to engage in a dialogue when the Government makes it a priority," he said.

The development of the country's oil and gas reserves is a priority in the Government's energy strategy which is now being finalised.