Montanwerke Brixlegg, the copper producer of Austria's A-Tec Industries (ATEC.VI: Quote, Profile , Research), and Russian fund Strikeforce have submitted binding bids for Serb copper miner RTB Bor, Serb news agency Beta reported on Thursday.

The second tender for the bankrupt complex was issued in August with a minimum price of $340 million for two surface mines, one underground mine and a smelting and refining unit.

The buyer will have to commit to additional investment of at least $180 million.

Serb government officials have refused to comment on the submitted bids. A statement from the country's Privatisation Agency confirmed only that two companies had bid, adding that their names would be revealed next week.

Apart from the Austrian and Russian firm, Britain's Vedanta Resources (VED.L: Quote, Profile , Research) , Cyprus-based East Point Holdings and Russian mining firm Solvej also bought tender documentation.

East Point openly pulled out of the race. Strikeforce, part of the Basic Element Group of Russian billionaire Oleg Deripaska announced their bid on Wednesday evening.

It had participated at the first tender for Bor, which was won by Romania's Cuprom. Cuprom later failed to pay up and pulled out of the deal, citing resistance from unions.

RTB Bor, run down during the war-torn 1990s, is estimated to have a debt of some $500 million, mostly to the state, and be losing about $45 million a year. Its outdated technology is seen posing a serious health risk to the region.