Tuscon-based Asarco, the third largest copper maker in U.S. had total revenue of $1.9 billion in 2007, Sterlite, a unit of Vedanta Resources Plc said in a statement.
"Asarco is a strategic fit with Sterlite's existing copper business," the Indian firm said in the statement.
On Friday a lawyer close to the deal had told Reuters in New York that Vedanta had signed a $2.6 billion deal to buy the assets of Asarco.
Asarco, formerly known as American Smelting and Refining Co, produced 235,000 tons of refined copper in 2007 and its mines have an estimated reserve of 5 million tons of contained copper.
It filed for bankruptcy protection in 2005 after it was sued for $1 billion over environmental and asbestos claim.
Sterlite, is India's top non-ferrous metals and mining firm with interests in aluminum, copper, zinc and lead.
The deal, subject to the approval of a U.S. Bankruptcy Court, will be funded through a mix of debt and existing cash, Sterlite said.
Last June, it had raised $1.75 billion in American depositary shares to pay for possible acquisitions and cut debt.
Indian firms coming of years of strong profitable growth and clean balance sheets that aid easy access to capital have been snapping up overseas firms to expand their presence globally.
Cellular firm Reliance Communications Ltd has started talks with South Africa's MTN MTN.J that could culminate in the creation of a $66 billion telecom group.
Tata Steel, last year engineered India's biggest takeover to date, a $13 billion purchase of Anglo-Dutch steel maker Corus Group and aluminum maker Hindalco Industries bought Canada's Novelis for $5.9 billion including debt.
Tata Motors in March agreed to buy the Jaguar and Land Rover Brands from Ford Motor Co for $2.3 billion.
Indian firm have announced outbound merger and acquisition deals worth $7.1 billion so far in 2008, Thomson Reuters data showed.
ABN AMRO advised Sterlite and it was Lehman Brothers for Asarco, the statement said.
Shares in Sterlite, which has a market value of $15.6 billion, ended 2.8 percent down at 934.90 rupees on Friday in a firm Mumbai market.