U.S. officials are investigating between six and eight embassy employees and dependents in Colombia to determine whether they used the mission's postal system to smuggle illegal drugs or other contraband to the United States, according to knowledgeable sources in Washington and Bogota.

The investigations began after the U.S. Army Criminal Investigation Division charged the wife of the officer in command of the U.S. military's counter-drug efforts in Colombia with shipping cocaine to the United States via the seldom-inspected government mail system.

The new inquiries were triggered during a follow-up review of embassy mailing records and have not led to criminal charges. But U.S. officials described the inquiries as particularly embarrassing, because Colombia produces 80 percent of the world's cocaine and most of the $289 million in annual U.S. aid to the South American country goes to combat drug trafficking.

Officials in Washington said the expanded investigation has added to concern about the U.S. Embassy in Bogota, which already was under scrutiny because of what several officials described as a dangerous, bunker-style mentality that is hampering implementation of new policy initiatives.

"Their performance has been very poor," said one official who deals with Colombia on a regular basis. "They are shutting down -- they seem unable to drive forward with any new policy initiatives. It is an embassy that sees itself as being under siege and it is acting like that."

Several officials went out of their way to praise Ambassador Curtis W. Kamman as an able career diplomat. But they said the embassy as a whole, grappling with growing security concerns from a Marxist-led guerrilla movement, often seemed paralyzed by internal disputes, interagency fighting and management problems.

Several months ago, the inspector general's office in the State Department began a congressionally requested review of the department's Colombia program, according to congressional and State Department officials.

The review centers on millions of dollars in U.S. aid given to the Colombian National Police over the past two years. Most of the money has gone to the police air wing, including about 40 helicopters and a handful of fixed-wing aircraft. The review is focusing on whether the State Department followed congressional guidelines.

"We have a very important embassy that has a lot of serious internal problems, and that is something we can't afford," said a congressional staffer who deals with Colombia issues. "It is just too important a country to allow ourselves to be embarrassed like this."

It is unclear whether the individuals being investigated for possible contraband shipments acted on their own or were involved in the previously disclosed case of Laurie Hiett, wife of U.S. Army Col. James Hiett. She was arraigned in Brooklyn on Aug. 5 on a charge of conspiracy to distribute narcotics, and released on $150,000 bond. She is accused of sending at least six packages, each containing about 2.7 pounds of cocaine, estimated by U.S. officials to be worth $235,000.

While acknowledging mailing the packages, Laurie Hiett has denied knowing what was in them. Her chauffeur, Jorge Alfonso Ayala, told U.S. investigators that Hiett abused cocaine, a charge she also has denied.

Hiett's husband has been cleared of any knowledge of the scheme, but he asked to be reassigned and has left Colombia, U.S. military officials said. Col. Hiett was in charge of the estimated 200 U.S. troops in Colombia involved in training Colombian security forces for counter-drug operations and protecting three large radar bases used primarily to track drug flights, one of the most important commands in Latin America. The Pentagon declined to reveal where he has been reassigned.

Knowledgeable sources said that among the people currently under investigation, one embassy employee is suspected of having a cocaine habit.

"They have been taking a hard look at the place," said one source, who said the continuing inquiry is an effort by federal and military investigators to follow up leads that they developed in the course of the Hiett probe.

U.S. officials acknowledged that embassy postal systems are easy to abuse because mail, delivered through the Army Postal Service (APO) by the U.S. Postal Service, is seldom inspected. In Bogota, the APO is located inside the embassy and is only available to embassy employees and their dependents.

An embassy spokesman in Bogota declined yesterday to comment on this story. Ambassador Kamman also had no comment.

In recent weeks senior Clinton administration officials have visited Bogota to express their growing concern over gains made by Colombia's leftist insurgents, who derive much of their financing from protecting drug traffickers and who have handed the military a series of devastating defeats in recent weeks.

Barry R. McCaffrey, the Clinton administration's drug policy director, said last week Colombia was in an "emergency situation" and has recommended that the U.S. invest another $1 billion in counter-drug efforts in the Andean region, with about half of it going to Colombia.

While details of the ongoing investigation remain murky, new details have emerged about Hiett, who was described by three people who knew her as being erratic, with sharp mood swings. Hiett's lawyer, Paul D. Lazarus, did not return telephone calls requesting comment yesterday.

One recently retired embassy employee who knew the Hietts well said the colonel had stopped taking his wife to social functions and told friends that her behavior had become an embarrassment.

"She was always a live wire, always hyper and she was a loose cannon," the source said. "She was initially invited to all social functions, but she would say the damnedest things, so for a long time the colonel had stopped taking her. She was always a potential embarrassment."

In Bogota, a parent and a school staff member at an international school where Laurie Hiett had been a substitute teacher, had similar assessments.

Fellow teachers "found her very erratic, and she had mood swings," the parent said. "She was always very hyper and complained like crazy about everything."

Kovaleski reported from Bogota, Farah from Washington.