RICHMOND, Va. — For the past five years, Senator Allen has failed to tell Congress about stock options that he got for his work as a director of a high-tech company. The Virginia Republican also asked the Army to help another business that gave him similar options.

Congressional rules require senators to disclose to the Senate all deferred compensation, such as stock options. The rules also urge senators to avoid taking any official action that could benefit them financially or appear to do so.

Those requirements exist so the public can police lawmakers for possible conflicts of interest, especially involving companies with government business that lawmakers can influence.

Mr. Allen’s stock options date to the period between January 1998 and January 2001 when Mr. Allen was between political jobs and had plunged into the corporate world.

An Associated Press review of Mr. Allen’s financial dealings from that era found that:

• The senator did not have to look far to find corporate suitors, joining three Virginia high-tech companies he assisted as governor. Mr. Allen served on boards of directors for Xybernaut and Commonwealth Biotechnologies and advised a third company called Com-Net Ericsson, all government contractors.

• He twice failed to promptly alert the Securities and Exchange Commission of insider stock transactions as a Xybernaut and Commonwealth director. The SEC requires timely notification and can fine those who file late.

• He kept stock options provided to him for serving as a director of Xybernaut and Commonwealth but steered other compensation from his board service to his law firm.

Mr. Allen, a potential 2008 presidential candidate, rose to prominence as a conservative from Virginia, serving in the U.S. House and as governor. Between 1998 and 2000, he worked as a private lawyer and businessman before joining the Senate in 2001.

He now faces a tough re-election campaign against Democrat Jim Webb. In interviews, Mr. Allen and his staff sought to play down his corporate dealings, saying they were a good learning experience but did not lead to extraordinary riches — except for a quarter-million-dollar windfall from Com-Net Ericsson stock.

Mr. Allen’s office said he sold his Xybernaut stock at a loss and has not cashed in his Commonwealth options because they cost more than the stock is now worth. The senator also said he saw no conflict going to work for companies shortly after assisting them as governor.

“I actually got no money out of Xybernaut. I got paid in stock options, which were worthless. Commonwealth Biotech asked me to be on their board. Glad to do it. I learned a lot on their board and enjoyed working with them, and they seem to be doing all right, I guess,” Mr. Allen said.

Mr. Allen’s office said he did not report his Commonwealth options on his past five Senate disclosure reports because their purchase price was higher than the current market value. Mr. Allen viewed them as worthless and believed in “good faith” he did not have to report them, aides said.

Mr. Allen disclosed the options once — on an amendment to his 2000 ethics report filed three months after the normal filing period ended. He excluded the options from subsequent reports.

When AP showed Mr. Allen’s lawyer the Senate ethics manual requirement that such options must be reported each year regardless of value, the lawyer said he was unfamiliar with that provision. Mr. Allen has now asked the Senate ethics committee for an opinion on whether he should have disclosed them.

“While we continue to believe that we have disclosed more than is required, we will abide by the formal ruling of the committee,” Mr. Allen’s spokesman, John Reid, said.

The disclosure requirements exist so the public can watch for potential conflicts of interest, and Mr. Allen had an obligation to report his Commonwealth stock options to Congress, two ethics experts said.

“As an ethical matter, it’s irrelevant whether the exercise price of those stock options is above or below the current market price of the stock,” a Washington University of St. Louis law professor, former prosecutor, and former Democratic congressional aide, Kathleen Clark, said.

“If he owns stock options, he does have such a financial stake, whether the exercise price is above or below current market value.”

Lawyer Marc Elias, who represents Democrats in ethics cases, said the conflict issue is even clearer because Commonwealth gets federal contracts.

“Unlike some other controversies that have come up from time to time, this is a situation where the underlying asset is in a company that has business before Congress,” Mr. Elias said.

Commonwealth granted Mr. Allen options on 15,000 shares of company stock at $7.50 a share in May 1999, company chief executive Robert Harris said.

The company’s stock has a history of wild fluctuations, typically rising after new government contracts. It hit between $9 and $10 a share the month after Mr. Allen left the board. It has been closer to $2 recently.

Commonwealth usually gives departing directors just 90 days to exercise stock options, but Mr. Allen’s were extended until as late as May 2009 because he was entering public service, Mr. Harris said.

When Mr. Allen left for the Senate, Commonwealth made clear it hoped he would help the company in his new job. “We, of course, wish him much success in Washington and look forward to his probusiness agenda reaping benefits for CBI, the commonwealth and the nation,” company chairman Richard Freer said.

Both Commonwealth and Xybernaut have suffered through difficult times and federal contracts have been an important financial lifeline in recent years.

Mr. Allen’s office acknowledges he has met socially over the years with company executives and his office has granted “routine courtesy meetings” from company lobbyists “to hear their opinion on legislation and issues before the federal government.”