The company’s offer represents a premium of more than 55% to Hathor’s unaffected closing price on 25 August 2011.

Rio Tinto said it is also a premium of about 11% to Cameco’s unsolicited offer of C$3.75 ($3.68) per common share, which was extended until 14 November 2011.

Rio Tinto plans to accelerate the investigation and assessment of Hathor’s exploration properties to unlock their full potential, consistent with global safety and community standards.