Petra Diamonds swung to an annual profit driven by a rise in revenue and production along with tight cost control and operational expansion. Net profit after tax came to $27.9m for the year to end of June compared to a 2012 loss of $2.1m as revenue jumped 27% to $402.7m from $316.9m. Adjusted earnings before interest, tax, depreciation and amortisation (EBITDA) was up 36% to $122.4m from last year's $90.3m.Profit from mining activity increased 34% to $138.6m from $103.3m as production grew 21% to 2,668,305 carats.During the year, the company invested $198.3m in expansion programmes which boosted output. "Fiscal year 2013 marked a further year of solid growth in terms of production, revenue and the underlying profitability of the group, as well as the acceleration of our major expansion programmes at Finsch and Cullinan, in line with expectations," said Chief Executive Officer, Johan Dippenaar. "We have kept our costs and capital expenditure well controlled, maintaining our robust financial position. We continue to deliver on our strategy to build a world-class diamond group, with production of circa 3m carats expected for fiscal year 2014, rising to 5m carats by fiscal year 2019."However, the firm warned that certain South African mines were affected by industrial action on August 29th. The industrial action has ended and normal operations are expected to be up and running from Monday.Looking ahead at the market conditions, the rough diamond industry is anticipated to remain steady in the fiscal year 2014 due to constrained supply and a firmer US sector and continued growth in China.RD