U.S. Sen. Edward M. "Ted" Kennedy said yesterday that he was stopped and questioned at airports on the East Coast five times in March because his name appeared on the government's secret "no-fly" list.

Federal air security officials said the initial error that led to scrutiny of the Massachusetts Democrat should not have happened even though they recognize that the no-fly list is imperfect. But privately they acknowledged being embarrassed that it took the senator and his staff more than three weeks to get his name removed.

A senior administration official, who spoke on condition he not be identified, said Kennedy was stopped because the name "T. Kennedy" has been used as an alias by someone on the list of terrorist suspects.

While he worked to clear himself, Kennedy kept having to wait in terminals at Reagan National, Boston's Logan International and at least one other airport, his staff said. All of the flights were on US Airways. When the senator checked in at the counter, airline employees told him they could not issue him a boarding pass because he appeared on the list. Kennedy was delayed until a supervisor could be summoned to identify him and give approval for him to board the plane.

Kennedy's description yesterday of his air-travel troubles -- mentioned during a Senate Judiciary Committee hearing on the 9/11 commission's recommendations -- renewed questions about the quality and effectiveness of the no-fly list. The list was established by security, intelligence and law enforcement agencies after the 2001 terrorist attacks. Critics said the senator's experience served as the latest example of how a system designed to improve security is instead targeting innocent travelers.

The government does not make public the names or the total number of people on the list, which officials say is constantly updated. According to FBI documents obtained by the American Civil Liberties Union under a Freedom of Information Act request, more than 350 Americans have been delayed or denied boarding since the list's inception. The list has not led to any arrests, officials said.

The ACLU has sued on behalf of six Americans who have had experiences similar to Kennedy's. The travelers suing the government include a Vermont college student, a retired Presbyterian minister and an ACLU employee.

"That a clerical error could lend one of the most powerful people in Washington to the list -- it makes one wonder just how many others who are not terrorists are on the list," said Reginald T. Shuford, senior ACLU counsel. "Someone of Senator Kennedy's stature can simply call a friend to have his name removed but a regular American citizen does not have that ability. He had to call three times himself."

A Kennedy aide said the senator nearly missed a couple of flights because of the delays. After the first few incidents, his staff called the Transportation Security Administration, which maintains the no-fly list. But even after those discussions about getting his name removed, the senator was stopped again, according to Kennedy spokesman David Smith. Homeland Security Secretary Tom Ridge finally called to apologize about the mix-up, and the delays stopped in early April, Smith said.

"If his name got on the list in error, is that happening to other citizens and are they experiencing such difficulty in resolving the problem?" Smith said.

TSA spokesman Mark Hatfield said the no-fly system occasionally causes problems because the airlines are responsible for identifying passengers who show up on the list.

"Administration of the list clearly needs to be changed and consolidated to be government-managed," Hatfield said. "This points out the weakness in having the names checked against passengers at hundreds of different airlines at thousands of different airline counters across the country."

The TSA has been working on a system for screening airline passengers that it says will improve the no-fly list. But the plan has been delayed by technological challenges and privacy concerns and the agency has not said when it will be ready.

US Airways declined to comment on Kennedy's experience, though it acknowledged that he is a well-known traveler on the airline. Two years ago, Kennedy helped persuade US Airways officials to reinstate the airline's "executive service" at Reagan National, which allows VIPs to be escorted to private lounges by airline employees.

About the no-fly list, the airline said yesterday in a written statement: "If passengers are identified for screening, that is a TSA decision and not up to the individual airline."

The TSA said passengers who have been tripped up by the list can contact the agency's ombudsman and obtain a letter to show airline and security officials that they have been cleared.

David C. Fathi, who said he is apparently on the no-fly list, obtained such a letter but said it hasn't done him much good. "By the time I show the letter, it is already too late," he said.

Fathi, a U.S. citizen of Iranian ancestry and an ACLU attorney, said he has been stopped seven or eight times at airports, but not on every flight. Once he was led from the counter by armed police and questioned extensively at the airport.

"There really is a no rhyme or reason" to getting delayed, Fathi said. "It illustrates the ridiculousness of the system. If it stops them because they're on the list they should stop them every time. Not every third time."