Washington ? An FBI agent accused her Washington headquarters of erecting a “roadblock” to the pre-Sept. 11 investigation of terrorism defendant Zacarias Moussaoui. Her letter immediately prompted an internal investigation.

Agent Coleen Rowley, a lawyer in the Minnesota office that arrested Moussaoui last August, divulged in her letter that local agents became so frustrated with FBI headquarters that they broke from their chain of command and notified the CIA about the suspect before Sept. 11.

The local agents were reprimanded for doing so, Rowley alleged in a rare letter to FBI Director Robert Mueller that also was sent Tuesday to the Senate Intelligence Committee.

“When, in a desperate 11th-hour measure to bypass the FBI HQ roadblock, the Minneapolis division undertook to directly notify the CIA’s counterterrorist center, FBI HQ personnel chastised the Minneapolis agents for making the direct notification without their approval,” she wrote in the 13-page letter, excerpts of which were obtained by The Associated Press.

Mueller immediately referred the matter to the Justice Department’s internal investigator, acknowledging his agency needed a “different approach” to fighting terrorism. Senators opened their own inquiry into the allegations.

Moussaoui, a French citizen or Moroccan descent, is the only person charged as an accomplice with Osama bin Laden and the 19 hijackers in the suicide hijackings. He was arrested in August after arousing suspicions with his flight training.

Prompted by Rowley’s disclosures, government officials confirmed Thursday night that the CIA received at least two pre-Sept. 11 contacts from the FBI concerning Moussaoui.

In mid-August, the FBI told CIA of concerns Moussaoui might be a terrorist, and the CIA checked its own files and found nothing on him. CIA also made a routine request from foreign governments that yielded intelligence from France that Moussaoui was a known Islamic extremist.

The second contact came in late August, when FBI agents in Minnesota told CIA officers they were seeking a warrant on Moussaoui, the official said.

Government officials familiar with Rowley’s letter said the agent alleged FBI headquarters did not fully appreciate the terrorist threat Moussaoui posed and hindered local agents’ efforts to get warrants to gather more evidence.

Senators reacted sternly to the latest controversy to strike the FBI, which also failed last summer to heed another agent’s warning in Phoenix that Arab students were training at U.S. aviation schools and schools nationwide needed to be checked.

“While I’m shocked at the seriousness of these allegations, this kind of problem from headquarters is no surprise,” said Sen. Charles Grassley, R-Iowa, a frequent FBI critic. “The FBI for too long has discouraged agents from using anything besides outdated tactics from the era of chasing Bonnie and Clyde.”