Mountain Province Diamonds, the Canadian exploration firm in which financier Dermot Desmond has an almost 25 per cent stake, is finalising the acquisition of a smaller rival that will boost its share of the world's largest new diamond project beyond 46 per cent.

Mountain Province, which has a market capitalisation of 220 million Canadian dollars (€143.4 million), has agreed in principle to acquire the outstanding stock of Camphor Ventures, in which it already holds a 33 per cent interest. Details of the purchase, expected to be released last week, remain to be announced.

Camphor has a market capitalisation of over C$22 million.

Mountain Province and Camphor Ventures are joint owners with De Beers of the Gahcho Kue diamond field in Canada's Northwest Territories. Camphor currently has a 4.9 per cent holding in the development, while De Beers has a 51 per cent stake, with Mountain Providence holding the balance

Mr Desmond has retained a holding in Mountain Province for a number of years and is represented on the board by Jonathan Comerford, who serves as chairman.

Another Dublin businessman, Desmond Sharkey, owns just under 10 per cent of the company.

Mountain Province directors also include Scottish entrepreneur and mining magnate Harry Dobson, an associate of Mr Desmond. Both men are investors in a major oil refinery project in eastern Canada.

The Gahcho Kue field is expected to cost in the region of €400 million to develop and should be operational by 2011. De Beers is shouldering all development costs and has the right to increase its stake in the mine to 60 per cent subject to certain conditions.