Two mining entrepreneurs, Widespread Energy and Widespread Portfolios, say they are seeking agreement with Crown Minerals on revised permit details for a prospecting licence over seabed minerals on the Chatham Rise.
The two companies jointly applied in August 2007 for prospecting rights over a 3048km area, 600km east of Christchurch, which includes seabed deposits of rock phosphate.
The deposits, also known as phosphorite, are at depths of about 400m.
But approval for the prospecting permit has been delayed while the Government develops suitable guidelines for regulating marine mining and mineral exploration.
In the 1980s, Fletcher Challenge investigated mining some of the 100 million tonnes of phosphorite deposits spread along 400km of seabed on the Chatham Rise - variously valued at between $10 billion and $50 billion - as a potential substitute for imported rock-phosphate used in fertiliser.
Widespread Portfolios said last year it had been approached by major fertiliser companies and international mining groups interested in its application.
Widespread Portfolios has a 26.7 percent stake in Widespread Energy.
The area covered by the consortium's licence application was later reported to have been surrounded by a subsequent application of 71,750sq km by Auckland company Chatham Phosphate.
Today, Widespread Portfolios managing director Chris Castle said there was "strong corporate interest" centred on the potential of a major new rock phosphate source. Rapid increase in demand for biofuels is boosting demand for fertilisers and ongoing increases in fertiliser prices.
The Widespread Joint Venture (90 percent Widespread Energy, 10 percent Widespread Portfolios) plans a two-year work programme that, if successful, will be followed by more detailed exploration and evaluation.
This will include feasibility studies updating the work done 25 years ago for Fletcher Challenge.
Mr Castle said advances in technology including global positioning systems (GPS) now make it possible to precisely mine the seabed with automated equipment.
And recent major increases in the market value of rock phosphate - from $US50 ($NZ80.8) a tonne to $US375/tonne in the past two years - made such mining more likely to be profitable.
Virtually all of the rock phosphate used by the New Zealand fertiliser industry is imported from Morocco, and increasing freight costs are adding to costs.
"A New Zealand-based and owned resource could well benefit all farmers and other stakeholders in the agricultural sector by lowering fertiliser prices and also reducing the exposure of the sector to exchange rate fluctuations and increasing transport prices," said Mr Castle.
NZPA