Chinalco has registered for the $15.2-billion rights issue of global miner Rio Tinto, but the State-owned non-ferrous mineral processor has not yet made up its mind on whether it wants to participate in the world's fifth largest rights issue or not.

According to the prospectus released by Rio Tinto on Tuesday, June 15 was the registration deadline for the issue. A Chinalco insider confirmed on June 16 that the company had completed the registration process, reported by Caijing, a business magazine of China.

"Completion of the registration means our company is entitled to buy the shares at any time, but we haven't decided whether to buy them or not," the insider, who did not wish to be named, said.