In confirming the discussions, Amur noted "press speculation that a potentially interested party has valued the company at an indicative price of up to £100 million".
Amur said the sale discussions are for "approximately the indicated price".
Irosta Trading owns Amur's principal Kun-Manie asset in the Amur Oblast of the Russian Far East.
"There can be no certainty that any agreement will be reached in respect of the proposed disposal, nor as to the terms of the proposed disposal," Amur said.
Amur's share price surged to £3.50 on January 25, up from £2.08 the day prior, and from £1.75 a week earlier. It closed trading on January 26 at £3.45/share.
Amur had a market capitalisation of £48.30 million.
On its website, Amur said that the Kun-Manie project was one of the largest potential sulphide nickel operations in the world, "which could place it among the top-10 nickel-producing companies on an annual basis".
Kun-Manie has a 155.1 million ore tonne resource within four deposits, containing recoverable nickel, copper, cobalt, platinum and palladium, Amur said.
The average nickel-equivalent grade is 1.02% and total nickel-equivalent tonnage is 1.58Mt, the company said.
