London-based resources giant Rio Tinto on Tuesday confirmed that it had applied to the UK Takeover Panel executive to set a deadline by which rival group BHP Billiton must either announce a firm intention to make an offer for Rio, or announce that it does not intend to make an offer.
Rio Tinto is defending itself against an unsolicited approach from the world's biggest resources group, which is offering three of its own shares for every Rio Tinto share.
BHP Billiton said last month that it had written to Rio Tinto with an offer at a premium, and had asked to meet with the company to discuss the proposal, but Rio Tinto had turned it down.
Rio Tinto says the offer undervalues it, and CEO Tom Albanese has described the proposal as "dead in the water".
If the Takeover Panel grants Rio Tinto the ruling it is seeking and BHP does not indicate a firm intention to make an offer before the deadline passes, the company would be barred from pursuing an offer for Rio Tinto for a period of six months.