A special committee formed by New Zealand’s Environmental Protection Authority (EPA) rejected Trans Tasman Resources Ltd’s plan to mine iron ore deposits off the coast of New Zealand. 

The decision was based on the “the uncertainties in the scope and significance of the potential adverse environmental effects and those on existing interests,” the environmental agency said in a statement.

Trans Tasman Resources Ltd had sought the final go-ahead to excavate iron sands from the sea bed in waters up to 45 metres (149 feet) deep off the country's west coast, but was turned down by a special committee set up by the EPA. If it had won approval, it would have been the first major offshore mining operation in the world.

Other governments and mining companies looking to mine copper, cobalt manganese and other metals from the sea floor were keeping a close eye on the decision, The New York Times reported.

Mining of diamonds currently takes place off the coast of Namibia, but the Trans Tasman project was one of the more advanced being proposed elsewhere.

Environmental groups, fishing companies, and local indigenous Maori tribes had opposed the project because of the potential damage to the environment, marine mammals and fish stocks.

Trans Tasman Resources said it was disappointed by the decision, having spent about NZ$60-million ($52-million) on the project so far, and having undertaken significant local consultation, and scientific research.

Chief executive Tim Crossley said in a statement the local community would miss out on hundreds of new jobs and an estimated NZ$240-million a year boost to GDP.

The company would study the ruling and look at its options. The decision can only be appealed on points of law.

Environmentalists called the outcome a victory for common sense.

"It became very clear during the hearings that the company ... had not done its homework on the full environmental impact of digging up 50 million tonnes of the seabed every year for 20 years," said Phil McCabe, the chair of Kiwis Against Seabed Mining.

A second New Zealand deep sea mining project was tabled last week by Chatham Rock Phosphate Ltd seeking to take phosphate rock to be turned into fertiliser in waters up to 400 m (1,200 ft) deep about 450 km (280 miles) east of the country.

The application will now undergo a six-month investigation period, including public and scientific submissions.