An Indian outsourcing company with thousands of employees in the United States is facing an expanding investigation prompted by claims from an American whistle-blower that it misused short-term visitors' visas to bring in low-cost workers from India, The New York Times reported Wednesday.

Accusations that the company, Infosys Technologies, repeatedly violated the terms of business visitor visas were first raised in a lawsuit filed in February in Alabama by Jack Palmer, an Infosys project manager, the newspaper report said.

Aside from Palmer, at least two other Infosys managers in the US have submitted internal whistle-blower reports pointing to Indians on business visitor visas who were performing longer-term work not authorized under those visas, the newspaper said, citing internal documents and current Infosys managers.

In May, Infosys acknowledged that it had received a subpoena from a federal grand jury in Texas seeking information about the company's use of the visitor documents, known as B-1 visas, which are easier to obtain.

This month, N. R. Narayana Murthy, an Infosys founder, expressed his concern about that investigation at a board meeting in Bangalore, India, in his final address before he retired as company chairman.

"As I leave the board, I feel sad about the subpoena, he said. The issue will be decided on its merits in due course," said Murthy, who is something of a legend in global business for building the company over three decades from a $250 investment into an outsourcing powerhouse with $6 billion in revenues.

In papers filed in Palmer's lawsuit, Infosys denied all his accusations and asked a federal judge to remove the dispute from court and send it to arbitration.

In a statement, Infosys said it was committed to absolute compliance with American visa requirements and had undertaken an internal review of its practices. The Infosys inquiry coincides with a broader attack in Congress on longer-term visas, known as H-1B, that Infosys and other Indian companies rely on to bring Indian technology workers to the United States.

With unemployment for Americans stubbornly high, lawmakers have become increasingly reluctant to defend H-1B visas, which give temporary residence to highly skilled foreigners. In recent years, the top companies receiving those visas were not American names, but Infosys and another big Indian outsourcing company, Wipro.

Last week, Congressman Zoe Lofgren, the senior Democrat on the immigration subcommittee of the House Judiciary Committee, introduced a bill that would increase the wages employers would have to pay H-1B workers, in an effort to ensure they do not undercut Americans.

The measure is specifically aimed at Indian outsourcing companies. Last year, Congress added an extra $2,000 to the fee for H-1B visas, in another move aimed at the Indian companies.