Q1 Production Report 2005

Antofagasta PLC 27 April 2005 The following statement has been released by Antofagasta plc and is distributed in London by Bankside Consultants Ltd on behalf of the Company. Contact: Keith Irons, 020 7444 4155. 27 April 2005 Antofagasta plc Quarterly Production Report - Q1 2005 Highlights • Group cash costs reached a record low as a result of high molybdenum prices. • Group copper production reached 118,800 tonnes, 9.0% above 2004 Q1 but 4.7% less than the quarterly average in 2004. Q1 Q2 Q3 Q4 Acc Acc Full Year Group Total 2005 2005 2005 2005 2005 2004 2004 Total copper production ('000 tonnes) 118.8 118.8 109.0 498.4 Weighted average Cash costs (cents per pound) (8.0) (8.0) 41.9 24.3 Los Pelambres Los Pelambres produced 80,600 tonnes in the first quarter compared to 72,400 tonnes in Q1 2004 but 8.1% below the quarterly average for 2004. The reduction was due to lower grades, as forecast in the mine plan, which were compensated partly by higher recoveries and by increased throughput in line with previous quarters. Improved recoveries are being obtained from material now being mined which includes some primary ore which is metallurgically favourable for the flotation process. Costs for the quarter fell to a record negative 45.9 cents per pound as by-product credits of 109.9 cents more than outweighed underlying costs. The high by-product credit was partially offset by higher treatment and refining charges and to a lesser extent by lower copper grades. Molybdenum prices averaged US$31.4 per pound compared with US$16.2 per pound in 2004. El Tesoro El Tesoro produced 26,300 tonnes in the quarter 7.6% above the quarterly average of the previous year. This was mainly due to higher recoveries helped by improved quality of ore in the agglomeration prior to transfer to the leach pads. This was only partially offset by the slight fall in grades and the reduced quantity of ore treated. Cash costs rose to 57.8 cents per pound, a 10.3% increase over 2004. The main cause of this increase was a higher waste to ore ratio in accordance with the mine plan, as well as increased sulphuric acid and petroleum costs. Michilla Production of 11,900 tonnes in Q1 was 4.8% less than the quarterly average for the year 2004. This was a result of changes in the sequence followed in the mine plan due to operational factors in the underground mine, which will be resolved during the second half. These changes affected both the quantity and grade of ore extracted which were only partly offset by higher recoveries. Cash costs rose substantially from 85.6 cents per pound in 2004 to 102.4 cents per pound in Q1 2005, due to the lower production as well as higher prices for sulphuric acid, power and petroleum. Transport (FCAB) Tonnage carried of 1.5 million (both rail and road) marginally increased over the quarterly average for 2004. Water - Aguas de Antofagasta S.A. Water sales increased by 1.5% to 8.3 million cubic metres compared to the quarterly average for 2004. Q1 Q2 Q3 Q4 Acc Acc Full Year Los Pelambres 2005 2005 2005 2005 2005 2004 2004 Daily average ore treated 115.4 125.9 ('000 tonnes) 129.0 129.0 Average ore grade (%) 0.79 0.79 0.84 0.88 Average recovery (%) 91.0 91.0 87.4 89.1 Concentrate produced ('000 tonnes) 222.0 222.0 186.9 948.8 Average concentrate grade (%) 37.5 37.5 40.0 38.2 Fine copper in concentrate ('000 tonnes) 83.3 83.3 74.8 362.6 Payable copper in concentrate ('000 tonnes) 80.6 80.6 72.4 350.6 Payable moly ('000 tonnes) 2.2 2.2 1.8 7.9 Cash costs (cents per pound) (45.9) (45.9) 33.3 7.9 By-product credits (cents per pound) (109.9) (109.9) (25.8) (45.8) Q1 Q2 Q3 Q4 Acc Acc 2004 Full Year El Tesoro 2005 2005 2005 2005 2005 2004 Daily average ore treated ('000 tonnes) 24.8 24.8 24.2 25.4 Average ore grade (%) 1.34 1.34 1.35 1.35 Average recovery (%) 82.4 82.4 81.0 78.1 Copper cathodes ('000 tonnes) 26.3 26.3 24.0 97.8 Cash costs (cents per pound) 57.8 57.8 47.2 52.4 Q1 Q2 Q3 Q4 Acc Acc Full Year Michilla 2005 2005 2005 2005 2005 2004 2004 Daily average ore treated ('000 tonnes) 15.3 15.3 16.8 16.1 Average ore grade (%) 1.09 1.09 1.09 1.11 Average recovery (%) 76.1 76.1 75.2 75.4 Copper cathodes ('000 tonnes) 11.9 11.9 12.6 50.0 Cash costs (cents per pound) 102.4 102.4 81.2 85.6 Q1 Q2 Q3 Q4 Acc Acc Full Year Transport 2005 2005 2005 2005 2005 2004 2004 Rail tonnage transported ('000 tons) 1,126 1,126 1,056 4,479 Road tonnage transported ('000 tons) 348 348 375 1,414 Q1 Q2 Q3 Q4 Acc Acc Full year Water 2005 2005 2005 2005 2005 2004 2004 Water volume sold - potable and untreated ('000 m3) 8,265 8,265 7,937 32,575 For further enquiries: Desmond O'Conor, Antofagasta plc doconor@antofagasta.co.uk (44) 20 7808 0988 Hussein Barma, Antofagasta plc hbarma@antofagasta.co.uk (44) 20 7808 0988 Alejandro Rivera, Antofagasta Minerals arivera@aminerals.cl (56-2) 377 5145 Issued by: Keith Irons, Bankside Consultants keith@bankside.com (44) 20 7444 4155 This information is provided by RNS The company news service from the London Stock Exchange