The Labour Party has renewed its call for an inquiry into the controversial method for extracting oil and gas known as fracking.
Canadian oil and gas exploration companies TAG Oil and Apache are proposing to explore sites in Gisborne, Central Hawke's Bay and the Tararua district and questions have been raised about whether fracking will be used.
The method, which is already in use in New Zealand, involves pumping a mixture of water, sand and chemicals into wells at extreme pressure to break open cracks in rocks bearing oil or gas.
Labour's environment spokesperson Grant Robertson says international evidence suggests fracking can contaminate groundwater and he says the Government needs to hold an investigation into the potential impacts.
"I'm not convinced by what I've heard so far that New Zealand can go ahead with this without having a full investigation, getting the facts on the table and then deciding if we want to make the decision as a country to have fracking take place," he says.