The economic impact of a large oil or gas discovery in New Zealand has dominated the conversation at a meeting held in Dunedin.

Cameron Madgwick of the Petroleum Exploration and Production Association spoke with local business representatives about the prospects of further exploration.

He says any discovery of a near-offshore field could be worth more than $3b, helping create hundreds of jobs in the development phase.

However it's an idea that's already prompting opposition from environmental groups around the country, including those locally.