A split Montgomery County Council rejected yesterday a school board proposal to increase teacher salaries next year by 6 percent, a move that school officials said also ruled out raising wages of beginning teachers to $19,000 a year.

By a vote of 4 to 3, the council denied the board's request for an additional $7.4 million for fiscal 1987 on the grounds that the proposal would benefit mainly veteran teachers.

However, the council voted unanimously to spend an additional $2.5 million to raise salaries for starting teachers to $19,000.

But school officials said the council's approval of a higher salary for beginning teachers was illegal because it was not part of a contract negotiated between the school board and the county teachers union.

Under the previously negotiated contract, all teachers would receive a 3.7 percent increase next fall, which would bring wages for beginning teachers to $17,100.

Mark Simon, president of the Montgomery County Education Association, which represents 6,400 county teachers, asked the council to reconsider yesterday's decision. "I am shocked by this," Simon said. "I foresee a bitter end of the school year, a bitter summer, and a bitter opening of school . . . . "

County Executive Charles W. Gilchrist strongly opposed the plan to raise teacher salaries at all levels.

He disputed school officials' contention that there is a "crisis" in hiring new teachers because Montgomery County's starting salaries are lower than those of some surrounding school districts.

"It seems the facts don't warrant an expenditure of such enormous magnitude," he told council members.

"To scrap the existing contract, we would have to accept that there is an urgent problem," Gilchrist said in a written statement he submitted to council members.

"There is no evidence that a crisis exists, other than the kind that too often is manufactured in an election year," he wrote.

Four of the school board's seven members are running for reelection this year.

School officials predicted that the council's action would hurt the school system's efforts to hire 600 to 700 new teachers for the next school year because county salaries will not be as competitive with those offered by surrounding jurisdictions.

"For next year, until our competitive position is improved, we are going to have a difficult time filling vacancies with as many highly qualified teachers," said School Superintendent Wilmer S. Cody. "To say we do not have a problem is inaccurate and misleading."

Council members William Hanna, Scott Fosler, Rose Crenca and Neal Potter voted against funding the entire pay package, with David Scull, Esther Gelman and Michael Gudis supporting the proposal.

The school board last Friday announced it had broken a three-month stalemate with the teachers union and had reached agreement on a pay package for next year that raised salaries of all teachers.

The school board previously had offered to raise the starting salaries of new teachers to $20,000, but the union rejected the offer because it did not benefit all teachers.

Scull, who 1983 came out in favor of cutting teacher salaries, said he supported the proposal to raise all teacher salaries.

"Why is Montgomery County at $17,000 when everybody else is at $19,000 or $20,000?" he said. "How can you expect good people to work for Montgomery County? You can't."

But some council members say that while starting salaries could be improved, Montgomery County already has the highest average salary -- $31,300 -- in the state.

"I support increases in starting salaries but not in across the board because we have one of the highest average salaries in the state," Hanna said.

Crenca said although she favors raising starting teacher pay, she was bothered by the fact that they pay proposal was not presented to the council "until the 12th hour." The council is scheduled to adopt next year's budget at a hearing tomorrow.