WASHINGTON — Senator Reid, the Democrat leader, is awaiting word from the Senate ethics committee on whether he failed to properly account for a business deal that allowed him a $1.1 million windfall on land he hadn’t owned for three years.

Mr. Reid sought the opinion after the Associated Press reported that the senator didn’t disclose to Congress that he first sold the land to a friend’s company in 2001 and took an ownership stake in the company. He didn’t collect the seven-figure payout until the company sold the land in 2004.

Mr. Reid reported the 2004 transaction as a personal sale, never disclosing his earlier sale or the stake in the company. Jay Brown, a former casino lawyer whose name surfaced in a major political bribery trial this summer and in other organized crime investigations, engineered the Nevada Democrat’s deal. Mr. Brown has never been charged with wrongdoing, except for a 1981 federal securities complaint settled out of court.

Ethics experts told AP that Mr. Reid’s inaccurate accounting of the deal to Congress appeared to violate Senate ethics rules.

“Everything I did was transparent,” Mr. Reid told a Las Vegas news conference after the story was published. “I paid all the taxes. Everything is fully disclosed to the ethics committee and everyone else.As I said, if there is some technical change that the ethics committee wants, I’ll be happy to do that.” Land deeds obtained by AP during a review of Mr. Reid’s business dealings show:

• The deal began in 1998 when Mr. Reid bought undeveloped residential property on Las Vegas’s booming outskirts for about $400,000. Mr. Reid bought one lot outright, and a second parcel jointly with Mr. Brown. One of the sellers was a developer who was benefiting from a government land swap that Mr. Reid supported. The seller never talked to Mr. Reid.

• In 2001, Mr. Reid sold the land for the same price to a limited liability corporation created by Mr. Brown. The senator didn’t disclose the sale on his annual public ethics report nor tell Congress he had any stake in Mr. Brown’s company. He continued to report to Congress that he personally owned the land.

• After getting local officials to rezone the property for a shopping center, Mr. Brown’s company sold the land in 2004 and Mr. Reid took $1.1 million of the proceeds, tripling the senator’s investment.

Mr. Reid reported it to Congress as a personal land sale.

The dealings allowed Mr. Reid to transfer ownership, legal liability, and some tax consequences to Mr. Brown’s company without public knowledge, but still collect the payoff three years later.

Mr. Reid hung up the phone when questioned about the deal during an AP interview last week.

The senator’s aides said no money changed hands in 2001 and that Mr. Reid instead got an ownership stake in Mr. Brown’s company equal to the value of his land. Mr. Reid continued to pay taxes on the land and didn’t disclose the deal because he considered it a “technical transfer,” they said.

They also said they have no documents proving Mr. Reid’s stake in the company because it was an informal understanding between friends.

The 1998 purchase “was a normal business transaction at market prices,” Mr. Reid spokesman Jim Manley said. “There were several legal steps associated with the investment during those years that did not alter Senator Mr. Reid’s actual ownership interest in the land.”

Senate ethics rules require lawmakers to disclose all transactions involving investment properties and to report any ownership stake in companies.

A former Federal Election Commission official who oversaw government disclosure reports for federal candidates for two decades, Kent Cooper, said Mr. Reid’s failure to report the 2001 sale and his ties to Mr. Brown’s company violated Senate rules.

“This is very, very clear,” Mr. Cooper said. “Whether you make a profit or a loss, you’ve got to put that transaction down so the public, voters, can see exactly what kind of money is moving to or from a member of Congress.”

A former Democratic chief counsel of the House, Stanley Brand, said Mr. Reid should have disclosed the 2001 sale and that his omission fits a larger culture in Congress where lawmakers aren’t following or enforcing their own rules.

Mr. Reid and his wife, Landra, signed the deeds selling their full interest in the property to Mr. Brown’s company, Patrick Lane LLC, for the same $400,000 they paid in 1998, records show. Despite the sale, Mr. Reid continued to say on his public ethics reports that he owned the land until it was sold in 2004. His disclosure forms to Congress do not mention an interest in Patrick Lane or the company’s role in the 2004 sale.

Mr. Reid isn’t listed anywhere on Patrick Lane’s corporate filings with Nevada, even though the land he sold accounted for three-quarters of the company’s assets. Mr. Brown is listed as the company’s manager. Mr. Reid’s office said Nevada law didn’t require Mr. Reid to be mentioned in the filings.

“We have been friends for over 35 years. We didn’t need a written agreement between us,” Mr. Brown said.

The informalities didn’t stop there. Brown sometimes paid a share of the local property taxes on the lot Mr. Reid owned outright between 1998 and 2001, while Mr. Reid sometimes paid more than his share of taxes on the second parcel they co-owned.

And the two men continued to pay the property taxes from their personal checking accounts even after the land was sold to Patrick Lane in 2001, records show.

Ethics experts said such informality raises questions about whether any of Mr. Brown’s tax payments amounted to a benefit for Mr. Reid. “It might be a gift,” Mr. Cooper said.

Nevada land deeds show Mr. Reid and his wife bought the property in January 1998 in a subdivision created partly with federal lands transferred by the Interior Department to developers.

The government never owned Mr. Reid’s two lots, but the piece of land adjoining Mr. Reid’s property — a key to the shopping center deal — came from the government in 1994.

One of the sellers was Fred Lessman of Perma-Bilt Homes. Around the time of the 1998 sale, Mr. Lessman and his company were completing a federal land transfer that involved an Arizona-based developer, Del Webb Corp.

In the deal, Del Webb and Perma-Bilt bought environmentally sensitive lands, transferred them to the government and then got in exchange pieces of valuable Las Vegas land.

For years, Mr. Reid encouraged Interior to make land swaps on behalf of Del Webb. In 1994, Mr. Reid wrote a letter with other Nevada lawmakers on behalf of Del Webb, and then met with a top federal land official in Nevada. That official claimed he felt pressured by the senator. Mr. Reid denied any pressure. The next year, Mr. Reid collected $18,000 in political donations from Del Webb’s political action committee and employees.

In December 1996, Mr. Reid wrote a second letter on behalf of Del Webb, urging Interior to answer the company’s concerns. The deal came together in summer and fall 1997, with Perma-Bilt joining in.

In January 1998 — just days before he bought his land — Mr. Reid applauded the Lake Tahoe land transfers, saying they would create the “gateway to paradise.”

“This land investment was completely unrelated to federal land swaps that took place in the mid-1990’s,” Mr. Manley said.

Mr. Lessman said he never talked to Mr. Reid or asked for his help before the 1998 land sale, and only met the senator years later at a public event. “Any suggestion that the land sale between Senator Reid and myself is somehow tied in with the Perma-Bilt exchange is completely absurd,” Mr. Lessman said.