Global miner Rio Tinto beat its target to secure a 47 percent stake in Riversdale Mining with its A$3.9 billion ($4 billion) takeover offer, and will pay its sweetened offer.

The offer of A$16.50 a share depended on it getting to at least a 47 percent holding in Riversdale by late on April 6. Otherwise it was set to pay A$16 a share.

Riversdale's two other key shareholders, India's Tata Steel and Brazil's CSN , have held on to their combined 47 percent stake.

($1 = 0.965 Australian Dollars)

(Reporting by Sonali Paul and Ed Davies)