ARIS, July 25 — French intelligence officials say that Zacarias Moussaoui, the only man charged with crimes related to the Sept. 11 terror attacks, traveled to Afghanistan several times in the late 1990's to attend terrorist training camps and meet with Al Qaeda officials in Kandahar and Jalalabad.
The French officials said they suspected, as do some American investigators, that Mr. Moussaoui, a French citizen arrested on visa violations last August, was not meant to take part in the hijackings on Sept. 11. Instead, they said they believed Al Qaeda leaders planned to use him in a follow-up attack, perhaps hijacking an American international flight.
The French officials, who have dug deeply into Mr. Moussaoui's ties to the terrorist group, said they suspected that other Al Qaeda members who supported him remain in the United States and could still be planning an attack.
The group's members have probably gone underground, "waiting for the best time to attack again," one French intelligence official said.
After trying to plead guilty to charges that he conspired in the Sept. 11 attacks, Mr. Moussaoui withdrew the plea on Thursday, insisting that he had no role in the hijacking plot.
Mr. Moussaoui acknowledged in federal court that he was a member of Al Qaeda, the terrorist network set up by Osama bin Laden, and suggested he was sent to the United States to participate in a terrorist conspiracy. But Mr. Moussaoui said at a hearing on Thursday that while he might have associated with some of the hijackers, "it doesn't mean that I'm on the plane" with them.
The comments by the French officials are significant because they go beyond what had been disclosed about Mr. Moussaoui's ties to Al Qaeda. In the indictment, the American authorities noted that Mr. Moussaoui had been to a Qaeda training camp in Afghanistan, but little else was made public about his trips there.
One French official also said the French told the American authorities late last August that Mr. Moussaoui, who was arrested on Aug. 16 while in flight training in Minneapolis, was a member of Al Qaeda.
But top officials at the Federal Bureau of Investigation, which has been criticized for failing to seek a special warrant to search Mr. Moussaoui's belongings, insisted that the French at that time supplied only a general sense that Mr. Moussaoui was close to Islamic extremists.
Under federal law, the bureau would have been required to show that Mr. Moussaoui was tied to a specific terrorist group to obtain a warrant for the search. Bureau agents in Minnesota have said they thought the French information was sufficient for the warrant, and they have criticized their superiors at the bureau's headquarters for blocking their efforts to obtain it.
When agents searched Mr. Moussaoui's belongings after Sept. 11, they found videotapes on flying two types of 747 aircraft and data on crop-dusting. They also found the telephone number in Hamburg, Germany, for a roommate of Mohamed Atta, who is thought to have been the ringleader in the Sept. 11 plot, information that might have pointed them toward some of the hijackers.
In interviews this week, the French officials said their inquiries showed that Mr. Moussaoui had close ties with Al Qaeda and that elements of the network that helped the Sept. 11 hijackers probably supported him.
American prosecutors charged Mr. Moussaoui in the Sept. 11 attacks and identified him as a possible "20th hijacker," whose arrest on a visa violation kept him off a plane.
But some American investigators have said that there is little evidence linking him to the plot and that he may have been part of some other plot, a view the French share.
French officials point out that Mr. Moussaoui was interested in learning to fly the giant Boeing 747 aircraft often used on overseas routes, while the hijacked planes were other Boeing models. The French also noted that Mr. Moussaoui is of Moroccan descent, while the Sept. 11 hijackers were Arabs.
Mr. Moussaoui, acting as his own lawyer in pretrial hearings in federal court in Alexandria, Va., has made rambling statements in which he said he was loyal to Mr. bin Laden but was not involved in the Sept. 11 conspiracy.
Antiterrorism experts in Paris, who have long experience dealing with Algerian extremists, said the Sept. 11 plot could not have succeeded without other accomplices.
As an example, they said that Ahmed Ressam, a Qaeda operative who planned to set off a bomb at Los Angeles International Airport at the end of 1999, had many accomplices, including some in Canada, Belgium and Australia.
The French authorities began monitoring Mr. Moussaoui in 1996 when he was spotted with Islamic extremists. In 1999, the French put him on a watch list because they suspected he was involved in terrorist activities.
Mr. Moussaoui, who had been living in London, entered the United States in February 2001 and began taking flight lessons, first in Oklahoma and then in Minnesota just before his arrest.