BELGRADE (Reuters) – Phelps Dodge Corp visited Serbia’s sole copper firm this week, expressing an interest in conducting geological research and a willingness to help the firm exploit low-grade ore, the head of Rudarsko-Topionicarski Basen Bor (RTB Bor) said yesterday. «Phelps Dodge executives, one in charge of Asia and Europe, and the other for projects in the Balkans, visited us on Monday and Tuesday,» said Borivoje Stojadinovic, the head of RTB Bor. Besides the US-based company, the world’s largest diversified miner, BHP Billiton had also recently visited the remote eastern Serbian region, he said. «All three world copper giants, including Rio Tinto, have expressed their interest in doing business here,» Stojadinovic told Reuters by phone. «The three are interested in investing in geological research in the Crni Vrh site… and in Borska Reka, the deeper layers of the existing underground Jama pit,» he said. The loss-making group has been hampered by a lack of cash in its exploration of deposits in Borska Reka, Crni Vrh and Juzni Revir, Stojadinovic said in July. Phelps Dodge had also expressed a willingness to help RTB Bor find the best technology to exploit the low-grade ore the Serbian mining and smelting group produces, he said. RTB Bor, consisting of 18 firms, is undergoing a restructuring program to spin off non-core assets ahead of privatization. The firm, with a debt of $400 million and outdated equipment, was badly hit by wars and sanctions under Slobodan Milosevic’s rule in the 1990s and the State is now subsidizing copper production by $350-400 per ton to help RTB Bor stay afloat.