State civil service officials will scrap the results of a Boston firefighter promotional exam after an investigation of cheating allegations showed that numerous firefighters talked during the test, brought cellphones into the testing room, and took unusually frequent trips to the men's room, say two public officials briefed on the probe results.

Investigators from the state Human Resources Division interviewed 90 percent of the 186 firefighters who took the test Nov. 17 at a Quincy middle school, but they were unable to prove that any individual firefighters cheated, said the officials, who were briefed separately and spoke on condition of anonymity because they did not have permission to speak publicly.

Nonetheless, state officials determined that some firefighters acted inappropriately during the test and may have cheated, the officials said, leading to the decision to require another test.

A new test date has not been set. While more than 700 firefighters around the state took promotional exams that day, there were indications of possible cheating only at the Quincy site, where the exam for the Boston Fire Department test was administered. Only those firefighters will be required to retake the test.

The probe was prompted by an anonymous complaint in December that a group of Boston firefighters took turns going into a men's room at the Quincy middle school and sent answers via text message on their cellphones to colleagues in the testing room.

But the state's Human Resources Division, which administers civil service exams, does not have the power to subpoena phone records and none of the test-takers volunteered to submit them for review, one of the two officials said. As a result, the investigation did not produce evidence of cheating. None of the firefighters contacted refused to discuss the test with investigators; one of the officials said 10 percent of test-takers could not be reached.

The cheating allegations, reported by the Globe on Jan. 6, gave another black eye to the Boston Fire Department, which has been embroiled in controversy over possible impairment in the deaths of two firefighters in a restaurant blaze in August. In addition, there has been an 18-month-long dispute in contract talks, with the union opposed to drug and alcohol testing without a significant raise. And the Globe has reported that fire personnel have enriched themselves by exploiting policies for disability pensions and sick leave.

Boston Fire Commissioner Roderick Fraser Jr. said last night that he is disappointed by the findings of the exam investigation.

"I don't believe this behavior is indicative of Boston firefighters," Fraser said in a telephone interview. "I had hoped that the people who studied hard and showed up and took the test and did the right thing would not be punished for the actions of a few."

In addition to throwing out the Nov. 17 test results and conducting another test, the state Human Resources Division plans to tighten security during all civil service examinations, one of the officials said.

Officials are considering instituting the use of metal detectors, sign-in and sign-out sheets for bathroom breaks, and increasing the number of proctors at testing sites. They are also planning to ban cellphones and other communication devices.

Previously, test-takers were warned against bringing them into exam sites, but if they ignored that warning, they were instructed to place the devices under their desks for the duration of the tests.

Paul Dietl, who heads the Human Resources Division, declined to comment yesterday. The division handles civil service testing for police and fire departments across the state, including entrance exams and promotional tests designed to qualify police officers and firefighters as chiefs, captains, and lieutenants. The division also administers tests for guards at state prisons.

On Dec. 14, the division received an anonymous complaint describing the alleged bathroom-texting scheme at the Quincy middle school. The complaint did not name the individuals involved, one of the two officials said.

The Boston lieutenant exam is administered once every two years. It is highly competitive, with more than 100 Boston firefighters testing for about two dozen openings each year in the Boston Fire Department.

Lieutenants are responsible for evaluating fire scenes and determining tactics and strategy, considering factors such as structure type, wind conditions, temperature, and water availability.

To earn the post, firefighters must pass the rigorous written tests, which are tailored to the individual cities and towns. Boston's test last year covered material from seven text books, 50 sections of the Massachusetts General Laws, and four Fire Department handbooks. Subject areas include chemistry, physics, hydraulics, ladder and pump operations, building design, and major emergency response tactics.

Firefighters usually study for months before taking the exam. The Human Resources Division released test results for firefighters from other towns in recent weeks, but the Boston scores have been delayed pending the outcome of the cheating investigation.

It is unclear who will pick up the tab for the replacement test. Firefighters paid $125 each to take the Nov. 17 test, a total of $23,250 in Boston.

Fraser said he hopes the state will administer a new test within weeks. "We will work with the Human Resources Division to try and expedite another test date," he said. "I hope that future test venues will be more secure."