CAIRO, June 3 -- Egyptian intelligence warned American officials about a week before Sept. 11 that Osama bin Laden's network was in the advance stages of executing a significant operation against an American target, President Hosni Mubarak said in an interview on Sunday.
Using a secret agent they had recruited who was in close contact with the bin Laden organization, Mr. Mubarak said, his intelligence chiefs tried unsuccessfully to halt the operation.
Mr. Mubarak said his intelligence officials had no indication what the target would be and had no idea of the magnitude of the coming attack.
"We didn't know that such a thing could take place," he said, referring to the Sept. 11 attacks. "We thought it was an embassy, an airplane, something, the usual thing."
But, he added, to discover after the event that the terrorists were going to take airplanes and destroy buildings, "that is unbelievable."
Still, Mr. Mubarak's disclosure represents the first time a foreign leader has said that an intelligence service had penetrated Mr. bin Laden's network, Al Qaeda, to the extent that discussions about specific operations -- and whether they could be halted or postponed -- were under way.
Mr. Mubarak did not say whether he knew how American counterterrorism officials had reacted to the Egyptian warning, which a senior United States intelligence official denied was received. But Mr. Mubarak said he believed that security at the United States Embassy in Cairo was tightened in early September as a result of the warning.
"We informed them about everything," he said, referring to American intelligence officials.
Mr. Mubarak cited the warning as evidence that Egypt has become an increasingly valuable intelligence partner to the United States in the war against terrorism, especially since Sept. 11. It seemed possible he was seeking to burnish Egypt's credentials, which have been questioned in Congress, in advance of his visit to Washington this week.
"Maybe some congressmen were thinking, `What is Egypt doing?' " for the United States, he said. "There are so many things we cannot say, mainly intelligence information. We did a lot, but sometimes you have to do it quietly."
A White House spokesman declined to comment on Mr. Mubarak's remarks. The senior United States intelligence official, however, said the Central Intelligence Agency had not received any warnings from Egypt about a possible attack in the days before Sept. 11.
"The Egyptians gave us some threat information, earlier in 2001, of possible attacks against U.S. or Egyptian interests," the official said. "There was nothing about hijackings, nothing about an attack inside the U.S. It did not come in the days before 9/11."
Mr. Mubarak's statements come as indications grow that American officials were slow to interpret emerging signs of a Qaeda plot well before the attacks on the World Trade Center and the Pentagon.
Last week, Robert S. Mueller III, the director of the Federal Bureau of Investigation, acknowledged lapses in his agency. And on Sunday, government officials disclosed that the C.I.A. had learned about a Sept. 11 hijacker's connections to Al Qaeda many months before the attacks.
By Mr. Mubarak's recollection, Egyptian intelligence officials informed American intelligence officers some time between March and May of 2001 of Egypt's penetration of the bin Laden organization through the agent. While he referred in the interview broadly to "American intelligence," United States officials say the intelligence relationship between Egypt and the United States is handled through the C.I.A. station chief at the embassy in Cairo.
The agent established such close contact with Mr. bin Laden's organization that Egyptian officials tried to use the agent's influence to stop the attack.
"We knew that something was going to happen," Mr. Mubarak said. "We had good contact" with shadowy figures who had information about the bin Laden group's activities. "We started to use them, to tell them, `You can stop this,' " using any pretext, the president added, to try "to give ourselves time to realize what may take place."
The Egyptian president said his intelligence chiefs believed, based on the agent's information, that "something is going to happen in the U.S." or "to the United States, maybe inside the U.S., maybe in an airplane, maybe in embassies" outside the United States. "We couldn't know, we tried to know where, but this information" never reached them.
"I think this man, this agent, phoned the group of bin Laden, I don't remember who it was," Mr. Mubarak said. The agent was told, "No, no, no, it's difficult to stop it."
By this time, the president added, "It was one week before" Sept. 11, "because the wheels were going on, we couldn't stop it -- one week or four days, a very short time."
At a minimum, Mr. Mubarak's account adds detail and drama to a list of warnings about potential terrorist attacks that American intelligence agencies fielded in the days, weeks and months before Sept. 11.
Today, an Egyptian official, commenting on warnings about the Sept. 11 attacks, said, "There were indications that something was being prepared."
"There was information about some people planning an operation in the United States, against the United States, but you could not pinpoint where, how, when," the official said.
The official noted that there had been extensive cooperation between the two countries' intelligence services after the attacks, with the Egyptians helping even in such seemingly mundane matters as sorting out the welter of Arab names used by the hijackers. He declined to be more specific about further cooperation.
For years, Egypt's security services, like Jordan's and Saudi Arabia's, have closely cooperated with the C.I.A. on security issues. After the Soviet invasion of Afghanistan in 1979, Anwar el-Sadat, who was then the Egyptian president, opened the country's warehouses of Soviet-made weapons to the Carter administration to equip mujahedeen fighters in Afghanistan.
After Mr. Sadat was assassinated in 1981, Mr. Mubarak continued the close cooperation. Through the 1980's, the C.I.A. also worked closely with Egypt to thwart Libyan military pressure on Sudan. Counterterrorist cooperation has been a longstanding feature of the secret cooperation.
More recently, in late September, Mr. Mubarak said, Egyptian intelligence services told the United States of a plot by bin Laden associates to kill President Bush and other leaders who met in July in Genoa, Italy.
In describing the intelligence activities, Mr. Mubarak assumed some risk himself. Islamic fundamentalists tried to assassinate him several years ago, and the killers of his predecessor were Muslim extremists.
Egypt's top intelligence officer, Omar Suleiman, has become one of Mr. Mubarak's indispensable envoys, traveling to Washington this month to gather political intelligence on what Mr. Bush wanted to discuss with Mr. Mubarak during his visit and conferring with C.I.A. officials about how to overhaul the security services of the Palestinian leader, Yasir Arafat. Mr. Suleiman also traveled to the occupied West Bank last week to get a progress report on how Mr. Arafat was implementing those reforms.
Western officials here say that Egyptian intelligence officers have penetrated most of the Islamic fundamentalist groups that operate here.
Still, the Egyptian leader expressed strong concern that a rising tide of anti-Americanism and the unresolved Palestinian crisis would lead to an escalation of terrorism in the region and around the world.
"I am afraid of what's happening in the Middle East for the future," he said. "the seriousness of the situation" may "generate new kinds of terrorism against all of us, against the U.S., against Egypt, against Jordan."