A two-star Army general who works for the Joint Chiefs of Staff says that Secretary of Defense Harold Brown has decided not to forward a military report on the combat readiness of U.S. forces to Congress, and that Brown wants a new report format that "places greater emphasis on the positive factors of our readiness."

Pentagon spokesman Thomas Ross immediately denied the general's assessment, calling it a "complete garble and misinterpretation . . . of the secretary's views."

The assertions, which have escalated still further the bitter campaign debate over the state of U.S. military preparedness, are contained in a memo by Maj. Gen. James H. Johnson.

Johnson's memo, meant for internal staff distribution, was leaked to the press late Thursday. One of the two reporters who first reported on the memo says he found it on his desk at the Pentagon.

Yesterday afternoon, Ronald Reagan's top foreign policy adviser, Richard Allen, called a news conference and, on the basis of the news accounts, accused Brown of tampering with military professionalism and trying to lull Americans into a false sense of security.

In his memo, Johnson wrote that "the secretary of defense has decided not to forward our readiness report synopsis to Congress. He has expressed concern that our current readiness reporting formats only emphasize the negative aspects of our military readiness. The secretary has asked that we reexamine our readiness reporting system to develop a report format which places greater emphasis on the positive factors of our readiness."

Pentagon spokesman Ross says Brown never talked to Johnson, that the general got his information thirdhand, that no instructions have been issued for a change in the basic combat readiness rating system and that no decision has been made to withhold anything from Congress.

According to Ross, a special quarterly report on overall U.S. combat readiness is prepared within the joint staff. This is an internal document and is never sent to Congress. Other combat readiness reports are prepared by the individual services, also for internal use, but Congress can, and sometimes does, get these reports from the services.

Defense officials said a staff member of the House Armed Services Committee requested a summary, or synopis, of the joint staff report about a month ago. Then came a similar request by Rep. Carr (D-Mich.), chairman of the committee's readiness panel. It was decided initially to make the report available to Carr but not to send it to the staff member. Officials said no final decision has been made about sending the synopsis to the staff member.

The Johnson memo came to light in the midst of a growing debate over the nation's defenses and a flurry of leaked military documents that show generally low combat readiness in many units. While these reports show military concern, they also provide ammunition for Reagan's contention that Carter has let the nation's defenses slip.

Brown has tried to explain that the standards by which U.S. combat readiness is measured are really quite high and that the United States is much better prepared to fight under wartime conditions than some of the more ideal peacetime measurements suggest.

In a major speech in Texas Thursday, Brown tried to explain that these military reports -- which indicate among other things that six out of 10 U.S.-based Army divisions are not fully combat-ready -- are meant as internal guides to show where money should be spent and what equipment is needed. In that same speech, Brown tried to stress the positive, so Johnson's assessment of what he thought Brown meant does not appear to be wrong.

Ross said yesterday that Brown "is not asking for any change whatsoever in the readiness reporting system. He is suggesting we think aboukt having a parallel reporting system which would convey some of the other important factors that go into military capability."

Whatever the precise situation within the Pentagon on this matter, the issue has clearly created a dilemma for Brown and the White House, because stressing the positive frequently flies in the face of recent testimony on Capitol Hill that suggests a military less ready than the recruiting posters depict.