WASHINGTON (AP) _ The Federal Aviation Administration withdrew eight test problems for air traffic controllers after concern was raised that portions of the questions appeared to have fallen into the hands of students, officials say.

An FAA spokesman said Monday another two problems that have been targeted as part of an investigation into alleged cheating at the FAA's academy in Oklahoma City are scheduled for replacement within the next 60 days.

But agency spokesman Bob Buckhorn as well as senior officials at the FAA school reiterated that they do not believe any of the information obtained by students has compromised the laboratory testing process that accounts for about 60 percent of a student's grade.

''I am convinced that this (testing) program is not compromised. ... It's a performance type of situation that you cannot cheat on,'' Morris Friloux, the school's superintendent, said in an interview.

But sources close to the Transportation Department investigation say investigators have determined that some test information was compromised.

An interim advisory to the FAA from its inspector general's office concluded recently that material very similar to test problems was available to students, some of whom likely gained an advantage over others through its use, it was learned Monday.

Meanwhile, an analysis by the FAA academy's quality assurance office of a packet of problems surrendered by a student in March concluded ''the student had correct information pertaining to nine of the graded laboratory problems'' on which he was about to be tested, according to an internal memorandum obtained by The Associated Press.

''This means that nine of the 14 graded problems were compromised,'' supervisor Oliver Spires wrote in a memorandum dated May 8. He said that while some details of the test problem, such as flight numbers, were missing, the traffic ''situations'' facing the student were identical to those on some test problems.

Rep. Guy Molinari, R-N.Y., said in an interview that investigators from the inspector general's office have informed him they will conclude in their final report that test problems were compromised and that additional safeguards are needed.

Molinari said he urged FAA Administrator Donald Engen to suspend testing of controller students until all of the problems being questioned can be removed.

Senior officials at the FAA academy said in interviews that they have been closely monitoring test scores for unusual fluctuations that might indicate a problem was compromised, but have found no such evidence.

The laboratory tests, which have been the focus of the cheating probe, consist of a series of traffic management problems in which students must safely guide aircraft during a 30-minute period. A student is graded on five problems selected by instructors from a pool of problems. The performance test accounts for 60 percent of a student's grade.

Friloux called the quality assurance office's analysis, which he had requested last March, ''purely opinion'' and said test scores and academy pass-fail ratios show no marked increase during the times test material was supposed to have been available to students.

''How can someone say a program is compromised when 50 percent (of the students) are not making it?'' he asked.

On average, about 60 percent of the students pass the 13-week course, but during the last 12 months when test material supposedly was being circulated, the pass ratio fell below average four times and was barely 50 percent in May.

In three cases, the pass percentage exceeded 70 percent, but officials, citing higher aptitude scores, attributed the unusual success rate in those classes to a better quality of students.

Actual scores on the six laboratory problems were only slightly higher than average in 1986 and actually dipped several percentage points during the first part of this year.

Douglas Murphy, manager of the FAA school's air traffic branch, maintained that the test information found in student hands could be the product of copious notes passed on by students over the years instead of a security leak.

According to several sources, who spoke on the condition they not be identified, investigators have been unable to pinpoint a single source for the test material found so far.

A student who voluntarily surrendered a packet of test material last March, several days before taking the examination, told investigators he had received it from another student who got it from a third student.