Prince William County school officials yesterday proposed a 1987 fiscal plan that they said would boost salaries of school employes by 5 percent and allow the administration to hire 113 more teachers.

Superintendent Richard W. Johnson said his $145.2 million budget for the next fiscal year represents a 14.4 percent increase over this year. Most of the new money, he said, would go for raises and new teachers.

"The top priority is to continue to operate a quality program even though you are in a growing setting," Johnson said at a news conference yesterday. The county school system, the third largest in Virginia, is experiencing soaring enrollment in the midst of Prince William's continuing development boom.

But a representative of a teacher group yesterday attacked Johnson's claims, saying the pay hikes fall far short of the group's demands. "My initial view is that it is a strikingly poor prioritization of resources," said Cameron Yow, director of the Prince William Education Association.

Yow charged that Johnson's blueprint misspends state funding increases for education, which he said were intended for teachers. The county is expected to get $67.5 million from the state in the next fiscal year, a 12.1 percent increase over this year. Yow said that if all of the increased state funds were used to pay instructional personnel, it would amount to an increase of more than 14 percent per person.

"In our estimation the budget is clearly not consistent with the intent of the General Assembly," said Yow. "We just don't have an administration that listens to employe concerns."

Last year Prince William raised teacher salaries more than any system in Virginia, according to officials, increasing starting pay from $14,200 to the current level of $17,000, ranking it 11th among Virginia school systems. Under Johnson's plan, starting pay next year would be $19,000.

School officials yesterday said the proposed raise, along with other benefits, is a continuation of Prince William's bid to offer more competitive compensation. Yow took it as proof that the last year's gains were a "singular exception to the patterns of the previous four years." Teacher pay has been a key issue in Prince William because of the system's poor record in retaining teachers.

Because of recent salary increases, "We're no longer as easy to raid," said Richard Chapin, the associate superintendent for management. "In the past, we were a training ground for other jurisdictions."

Johnson said he is calling for 144 new school positions next year -- 113 of them teachers' jobs -- to accommodate the 1,300 new students he expects.

The proposed budget also provides a reserve fund to pay for 25 teachers if enrollment projections prove too low. Last fall, school officials scurried to hire teachers after the start of the school year, when opening day produced many more students than expected.

Other major new areas of spending in this year's budget, school officials said, are for school maintenance, which has traditionally been ignored because of competing priorities, and for skyrocketing insurance costs.

Johnson's budget now goes to the School Board, which is expected to act on it March 12. From there, the budget is incorporated into the total county budget, which must be passed by the Board of Supervisors.

Supervisor G. Richard Pfitzner said that he supports increased teacher salaries, but that it is unlikely "that a whole lot of money will be added that would satisfy Mr. Yow."