The sources said the assets were worth more than $2 billion.

"A sale is one of the options," one source said, speaking on condition of anonymity.

Two other sources said the assets were on offer and all three sources said Glencore had appointed Deutsche Bank and BMO Capital Markets as advisers.

Along with other big mining companies, Glencore is looking to sell assets to reduce high levels of debt following a plunge in commodity prices and a fall in Chinese demand for raw materials.

Quoting people familiar with the sale process, the Financial Times said Chinese miners were expected to lead the charge to buy the assets following a rebound in gold prices. One of the sources told Reuters it was far from certain there would be a deal.

"There's a very small field of buyers. None of the Western groups will touch it because it's based in Kazakhstan," the source said.

Glencore owns just under 70 percent of Vasilkovskoye.

(Reporting by Barbara Lewis and Freya Berry; editing by David Clarke)