Rio has been searching for extra funds after its purchase last year of Canadian aluminium group Alcan, which saddled the company with some 38 billion dollars of debt. But Chinalco's emergence as a suitor sparked a political firestorm over ownership of Australian assets, leaving the Australian government with a difficult choice -- to risk angering either its electorate or China, a key market. Instead, Rio unveiled an iron ore joint venture with BHP Billiton and a rights issue worth 15.2 billion US dollars. BHP meanwhile abandoned a hostile takeover bid for Rio last November.