Global miner Rio Tinto says it will extend its offer for shares in Riversdale Mining by three trading days.

Following discussions with market participants, Rio Tinto Jersey Holdings 2010 Ltd, a wholly-owned subsidiary of the Rio Tinto Group, will extend the $16.50 offer price increase by three trading days to 28 March 2011, if RTJ obtains an interest in more than 50 per cent of Riversdale shares, including institutional acceptances lodged under RTJ’s Institutional Acceptance Facility (IAF) by 7.00pm (Sydney time) on that date; and extend the offer period for its takeover bid for Riversdale by three trading days until 7.00pm (Sydney time) on Wednesday 6 April 2011, unless extended.

Rio said RTJ understands the additional time would allow some market participants to finalise the unwinding of equity swaps and to settle trades that have occurred on the Australian Securities Exchange (ASX) before they can accept into the offer or the IAF.

Since RTJ announced on 10 March 2011 the conditional offer price increase to $16.50, there has been a substantial increase in both the number of Riversdale shares covered by institutional acceptances lodged with the IAF, as well as additional direct acceptances of the offer. The total of the Riversdale shares in which RTJ has a relevant interest, plus shares subject to IAF instructions, was 34.94 per cent of the Riversdale shares on issue as at 9.00am (Sydney time) today.

The handling fee described in RTJ's third supplementary bidder's statement will apply throughout the extended offer period. RTJ may extend the period during which the Handing Fee will apply by further announcement released to ASX.

Terms defined in RTJ's bidder's statement for the bid have the same meaning in this announcement. The offer period for RTJ's Bid for Riversdale will close on 6 April 2011, unless extended.

Shares in Rio Tinto this morning was up 75 cents at $81.25, while Riversdale was 16 cents higher at $15.87.