DUBAI/BOSTON, May 12 (Reuters ) : Two companies with major operations in India were the weak links that opened the door to a $45 million global cyber heist brought to light by U.S. authorities this week.

EnStage Inc, which operates from Bangalore, and ElectraCard Services, which is based in Pune, processed card payments for the two Middle Eastern banks that were hit in the theft, according to several people familiar with the situation.

U.S. prosecutors said on Thursday that hackers broke into two card processing companies, raising the balances and withdrawal limits on accounts that were then exploited in coordinated ATM withdrawals around the world.

The prosecutors did not name the two companies but said one was based in India and the other in the United States.

According to a U.S. official and a bank employee, who both spoke on condition of anonymity, ElectraCard Services was the company that processed prepaid travel cards for National Bank of Ras Al Khaimah PSC RAKB.AD (RAKBANK). RAKBANK suffered a $5 million coordinated heist at ATMs around the world on December 21 last year, according to the U.S. indictment.

Ramesh Mengawade, the chief executive of ElectraCard Services and its parent company, Opus Software Solutions, could not be reached through his assistant or by email on Saturday. Calls to the mobile phone of another company official were not answered.

EnStage, which is incorporated in Cupertino, California, is the company that processed card payments for Bank of Muscat BMAO.OM of Oman, according to a source close to Bank of Muscat. Bank of Muscat lost $40 million in a coordinated heist on February 19, according to Thursday's indictment.

Officials at enStage could not be reached on Saturday, either in Bangalore or in Cupertino. In a statement in the Times of India, Chief Executive Govind Setlur said the company has implemented security enhancements and monitoring since the theft.

"Our customers were adversely affected by this sophisticated crime," Setlur said in the statement. "We are deeply committed to information security, and we will continue to take all reasonable measures to ensure our networks are secured from criminal actors."

MORE WORK FOR BIG PROCESSORS?

Bank of Muscat has not commented on the case.

MasterCard (MA.N), the network under which the cards used in the heist were issued, has said its security was not compromised. MasterCard bought a 12.5 percent stake in ElectraCard in 2010, ElectraCard has said.

Cyber security experts said the global scope and speed of the $45 million bank theft was unprecedented. The global gang had operatives in 27 countries who fanned out to thousands of ATMs in a matter of hours, withdrawing money using fraudulent prepaid debit cards, according to U.S. prosecutors.

The U.S. Justice Department gave details of the heist on Thursday in an indictment against eight men accused of being the New York cell of the organization. The department said seven of the men have been arrested.

The ringleaders of the global operation were believed to be outside the United States, but U.S. prosecutors have declined to give details, citing the continuing investigation. Germany is the only other country so far to announce arrests.

Eddie Schwartz, chief information security officer for RSA Inc, a firm that helps banks fight payment card fraud, said that it is not surprising that hackers would target banks that rely on Indian firms to process transactions.

Schwartz, who is based in Washington, said there is not as much government oversight in India as there is in the United States and Western Europe.

"Hackers view India as a target. It's got a fast-moving economy, a fast-moving IT infrastructure," Schwartz said.

Madeline Aufseeser, a senior analyst with Aite Group who follows payments processors, said she was relieved to learn that the case appeared to be limited to smaller processors.

"It looks like an isolated, very targeted incident," she said, noting that the major firms in the industry have highly sophisticated protocols to limit fraud damages.

The big players include First Data Corp, FIS (FIS.N), Galileo Mastercard Inc's (MA.N) Mastercard Integrated Processing Solutions, Tsys (TSS.N) and Visa Inc's (V.N) Visa Debit Processing Service.

Philip Philliou, managing partner of Philliou Partners LLC, a firm that helps banks and retailers select payment processors, predicted smaller processing firms will lose business as a result of this theft. Banks will decide they are not willing to assume the additional risk that comes with using smaller firms, he said.