WASHINGTON (AP) _ The Pentagon, in the most thorough survey ever of attitudes in the military on race relations, suggests minorities remain pessimistic about their chances of advancement.

Defense Secretary William Cohen will instruct the military to ``make modifications and improvements'' to correct the situation, according to spokesman Kenneth Bacon.

The Pentagon was expected to release today the results of surveys sent to 76,754 active military members; more than 44,000 were returned.

In a preview of the report, Bacon said the survey results suggest that nearly three-quarters of all blacks and other minorities serving in uniform complain that they have experienced racially offensive behavior.

Less than half expressed confidence that complaints of discrimination are thoroughly investigated, according to the survey.

While whites generally took positive views of the situation on bases and ships, blacks, Hispanics, Asians and American Indians consistently expressed more negative assessments.

The 296-page, congressionally mandated survey was conducted in late 1996 and early 1997.

According to Bacon, the survey of randomly selected enlisted service members and officers shows that ``large majorities of service members in all ethnic groups believe that race relations at the time of the survey were as good or better than five years ago.''

In the survey, 9 percent of blacks, 6 percent of Hispanics, 5 percent of American Indians or Alaskan natives, 4 percent of Asian Pacific islander, but only 2 percent of whites, said they had been unfairly punished because of their race, the survey suggested.

Black members of the military feel they have a ``harder time building a folder or a record than white people do'' for advancement, Bacon said. This is particularly true in the lower ranks, he said.

Bacon said Cohen would issue instructions to the services today asking them to closely study the survey results to make improvements.

In the order, he said, the secretary will say that, ``I am convinced that this important survey can inform our actions as we work to improve our processes and practices that are designed to ensure equal opportunity for and fair treatment of all men and women in uniform.''