NEW YORK — Banished from the headquarters of the international insurance conglomerate he spent nearly 40 years assembling, Maurice R. "Hank" Greenberg is starting over at age 81.

This time, the ousted chairman of American International Group Inc. is building a privately held insurance firm, with an "emphasis on private," he said recently , with a wry nod to the regulatory troubles that led to his current position. Last spring, AIG's board severed ties with its longtime leader over a 2000 re-insurance transaction — initiated by Greenberg — that resulted in a Justice Department investigation and a civil fraud suit by New York Attorney General Eliot Spitzer. The suit is still pending, and Greenberg has denied any wrongdoing.

As his business empire was being taken away from him, Greenberg's influence also was waning in Washington, where he was used to being treated as a titan of not only American commerce but also of international relations and philanthropy.

A regular guest at White House state dinners in every presidency from Richard Nixon's to Bill Clinton's, Greenberg was involved in critical trade-treaty deals and helped procure the necessary insurance to allow commercial airlines to begin flying again after the Sept. 11, 2001, terrorist attacks. Blunt to the point of being abrasive, Greenberg stood out in Washington and diplomatic circles for his aggressive pursuit of his beliefs and his corporate interests.

"He's a tough guy. If you're afraid of conflict and pressure, then you're not going to work with Hank," said U.S. Chamber of Commerce president Thomas J. Donohue. "He never asked you to put your money where he wouldn't put his. He was a leader."

In the past few years, Greenberg has seen his ties to power weaken. He battled the Securities and Exchange Commission and engaged in a 2003 public spat with Treasury Secretary John Snow about the tax treatment of a product sold by the life insurance industry. One lobbyist said the White House had advised against using Greenberg as a point man on corporate and insurance issues because his manner had alienated too many people. (The lobbyist spoke on condition of anonymity for fear of alienating Greenberg and the administration.)

Greenberg has noticed the difference: "I don't have much to do with the current administration. I don't think they reach out much."

Things were different in earlier decades.

Born in New York in 1925, Greenberg lied about his age and joined the Army in time to storm the beaches at Normandy. He also served in Korea before joining the insurance business. Under his leadership, AIG became a worldwide industry leader and one of 30 stocks that make up the Dow Jones industrial average. Along the way, Greenberg earned a reputation as a take-no-prisoners negotiator whose tough manner drove his sons Evan and Jeffrey out of the family business into other insurance firms.

One of the first Americans to do business with China after relations were reopened in 1972, Greenberg had extraordinary influence there and in the rest of Asia. "I traveled with him to India and Uzbekistan. In both places, we met with the prime minister, and in Uzbekistan we met the premier. He was treated by them as if he were secretary of state," said Leslie Gelb, who was president of the Council on Foreign Relations while Greenberg was on the board.

Greenberg spent years cultivating Chinese officials, developing personal ties that lasted decades. After a first visit in 1975, he began a reinsurance relationship with the People's Insurance Co., which had a monopoly on Chinese business that it was not eager to relinquish. Four years later, he put together a joint venture to insure trade between the two countries.

In 1992 — 17 years after he began his campaign — AIG was granted the first foreign license to sell life insurance in Shanghai. Greenberg showed his appreciation. In 1993, the C.V. Starr Foundation (named for AIG's founder and chaired by Greenberg) bought a pair of bronze window panels that had been looted from Beijing's Summer Palace by invaders in the early 20th century and returned them to their home.

AIG gave Shanghai an anti-pollution barge that pumped oxygen into a polluted local waterway. Greenberg made sure the barge carried signs advertising AIG's Chinese life insurance subsidiary as it plied the murky waters.

"I was for many years struck by the contrast of this wiry, impatient, exacting personality entering Asia and toiling year after year to make any progress at all," said former U.S. trade representative Charlene Barshefsky. "There is sometimes a desire to pigeonhole him in ways that understate his range."

By the time China was negotiating with the United States and Europe over terms of entry into the World Trade Organization in 2000, AIG subsidiaries were licensed to sell insurance in four cities.

During the WTO treaty negotiations, Greenberg fought to keep AIG the only foreign insurance firm not required to take on Chinese partners. Zhu, who had become premier, offered AIG two new branches. Greenberg turned him down. When the Chinese sweetened their offer to include licenses in Beijing and Suzhou plus two branch offices, Greenberg acquiesced, and the treaty went through.

Greenberg remains actively involved in international affairs. He has made several trips to Asia to help build his new business, and in 2004, he visited U.S. troops in Iraq and met with the leaders of the republic of Georgia. "He strides the globe, and he does it because he knows how it works," said retired Air Force Gen. Chuck Boyd, who arranged the Iraq and Georgia trip.

Greenberg may have many more years ahead of him. "My great-grandmother was 108, and she worked until the day she died," he notes.