Norilsk Nickel has announced that its Norimet Limited subsidiary has extended its offer to purchase up to 4.35 million shares of the Stillwater Mining Co.

Shareholders now have until midnight on Saturday the 26th of August to accept or reject the offer, rather than until the 19th, the original closing date.

Norimet is offering $7.50 per share in cash for a majority stake in Stillwater. A preliminary count by the Bank of New York showed that 6,166,512 shares had been tendered by the 16th of August.

Stillwater shareholders voted in June to approve the sale of a majority stake to the Moscow nickel and palladium mining company Norilsk Nickel, following losses from its two Montana mines.

Stillwater Mining, America's sole producer of platinum and palladium, delivered results showing a net loss of $19.3 million for the second quarter, with the firm suggesting the transaction had impacted on its performance.

Norilsk has long been keen on purchasing the firm because of its platinum group metal reserves, but analysts also believe the company is keen to make itself appear more attractive to western investors through the deal.