The proposed plans come after the government extended the company’s mining license by 15 years until 2035.

Namdeb Diamond general manager Riaan Burger was quoted by Bloomberg as saying that the company plans to mine at its Elizabeth Bay, Southern Coastal and Daberasup operations.

"We can easily go up to end of license period if we get the cost structures right.

"With optimization of new technology, we are confident we can do more."

In 2013, the company’s marine mining unit extracted 1.16 million carats from the Atlantic Ocean floor, while its land-based operations produced around 600,000 carats.

Namdeb’s more than 1,500 workers are under strike demanding a 15% increase in wages, rejecting the company’s offer of a 10% increase.

Namdeb CEO Inge Zaamwani-Kamwi said: "The union’s demands will increase cost levels and this will have a detrimental effect on long-term sustainability of our operations."

The workers strike has resulted in loss of 1,600 carats output per day, the company said.