Global miner Rio Tinto Group (ASX: RIO) says its wholly-owned subsidiary Rio Tinto Jersey Holdings 2010 Ltd (RTJ) has obtained an interest in 49.49 per cent of all the shares of Riversdale Mining Ltd as of a short time ago. As a result, RTJ has now increased the offer price under its takeover offer for Riversdale to $16.50 cash per share.

Rio says, given the offer is now unconditional, Riversdale shareholders who have accepted the offer on or before today's date will be paid the offer price of $16.50 per share by 13 April 2011. Riversdale shareholders who accept the offer after today's date will be paid the offer price of $16.50 within five business days of that acceptance being received.

The offer period has also been automatically extended for a period of 14 days as a result of the offer price increase, so that it will now end at 7.00pm (Sydney time) on Wednesday, 20 April 2011 unless further extended.

Rio said RTJ urges all Riversdale shareholders who have not yet accepted this unanimously recommended and unconditional offer to do so as soon as possible.