Organizers of the Millennium March on Washington said yesterday that they have not received any of the revenue promised by the company that produced the festival related to the event. The FBI confirmed that it is investigating allegations that someone might have walked off with the money, which could be about $750,000.

"We did receive allegations that the funds are missing," said FBI spokeswoman Susan Lloyd. "We have opened a preliminary investigation into this allegation. At this point, we have not independently confirmed any of it, including the amount of money or the people involved."

The accusations are the subject of online news articles and recriminations throughout the gay activist community. Organizers of the nonprofit Millennium March, held the last weekend in April, have not ruled out a lawsuit against Millennium Productions, a for-profit organization that agreed to turn over 65 percent of the revenue from the sale of food, souvenirs and tickets to entertainment events during the festival.

But Jose Ucles, director of Millennium Productions, said last night that he and his business partners were also "victims."

"We were robbed of half a million upwards, perhaps $750,000," Ucles said. "It had to be someone who knew us, and that is the sad part."

Ucles said he and his staff have been counting and recounting food, drink and entry tickets since the event, in an attempt to figure out exactly how much money is missing. He said he planned to send letters soon to vendors, explaining why they cannot be paid.

"Everything is on hold pending an ongoing investigation," he said.

Gay activist organizations are watching closely. "It's certainly a big event for us," said Robin Stevens, a spokeswoman for Online Partners, a San Francisco-based organization that operates Gay.com, an Internet news service that ran a story about the missing funds Monday.

"The Millennium March owes a lot of money to various organizations," Stevens said. "The amount of money missing is large. Those aren't easy amounts of money for anybody to swallow."

The Millennium March was organized as a celebration of gay pride. March organizers said Millennium Productions signed a contract to provide a series of for-profit events, and food and souvenirs during the events. In return, they said, festival organizers agreed to pay a percentage of proceeds to march planners.

The concerts, speeches and celebrity appearances went off without incident. But controversy over attendance arose among gay groups. Organizers said the April 30 event drew a crowd of 800,000. Opponents said the number was closer to 100,000.

"In spite of what we're talking about now, it was a wonderful march," said Ann DeGroot, co-chair of the committee that sponsored the event. "This march really had an incredible effect."

The dispute over funds began on the last night of the event. March organizers said members of Millennium Productions told them "that they couldn't pay us what they owe us," DeGroot said. "We think they owe us about $750,000."

At the end of the march, organizers said they realized that they had a major problem. Without the money, they couldn't hope to repay the money they borrowed from companies to stage the event. On Monday, they broke the news to other committee members. On Tuesday, they approached the FBI's Washington field office.

"It is fair to infer at this point that someone simply walked off with the money," said Michael Boucher, a lawyer with the Washington-based firm of McKenna & Cuneo who served as general counsel for the march.

Ucles's participation in the event raised the eyebrows of people like Bill Dobbs, a member of the New-York based Ad Hoc Committee for an Open Process, a group that is seeking financial information about the Millennium March. Dobbs said Ucles resigned from the Millennium March committee a few months before approaching the group to run a for-profit festival.

Dobbs said his committee is concerned about such occurrences. He said the committee has asked march organizers to open the march's financial books for public examination for the past three years. Each time, he said, march organizers refused.

Staff researcher Bobbye Pratt contributed to this report.