HAVANA, April 27 (Reuters)—Cuba will proceed with plans to build a ferronickel plant with its ally Venezuela, even though a dramatic drop in international prices has drained the island's foreign income, a government official said on Monday. Cuba produced some 70,000 tonnes of unrefined nickel plus cobalt in 2008. The mineral is mostly exported to China. The new $600 million ferronickel plant will be located in Las Camariocas, in Cuba's eastern province of Holguin where the island's nickel industry is based. Cuban officials have said in the past the plant could produce annually up to 68,000 tonnes of ferronickel, an alloy used in making stainless steel.