Republican Richmond M. Keeney and Democrat Charles W. Gilchrist accused each other yesterday of misleading the public about the promise of tax cuts and curtailed government spending if elected Montgomery County executive.

In a speech to the Montgomery County Press Association Keeney called the controversail 1-cent increase in the state sales tax of 1977 the "Gilchrist sales tax," because Gilchrist, as a state senator, voted for the legislation which passed by a one-vote margin.

Gilchrist retorted that the sales tax increase "was used for property tax relief amounting to $2 million for Montgomery County." Keeney's proposed tax abatement plan to roll back property tax rates 5 percent a year in merely a "pig in a poke," GIlchrist charged.

The candidates, who previously has rarely acknowledge the other despite many side-by-side campaign appearancaes, engaged in their first verbal exchange yesterday before the press association, other candidates and campaign workers at a luncheon in Gaithersburg.

Following the exchange, each candidate looked temporarily stunned. Gilchrist swore under his breath, shaking his head. Keeney conceded to a volunteer that it was "tough" taking the direct approach with an opponent.

The men then shook hands and smiled as if pleased at enlivening what has been criticized as a colorless race.

Keeney, the first to speak, set the pace with an item-by-item attack on Gilchrist's record over his four-year term in the legislature.

By contrast, Keeney said, his own term on the County council from 1966 to 1970 and his three years since 1973 on the planning board were experiences more relevant to local problems then Gilchrist's tenure in Annapolis.

Keeney charged that although Gilchrist, a tax lawyer, is advertised in his literature as a "recognized authority in the tax field . . . it is precisely in that field that we in Montgomery County have been bereft of leadership in Annapolis. On the surface he had the credentials. On the surface he served on all the right committees . . . But what has he done?"

Keeney listed Gilchrist's sponsorship of "another nuisance tax on high-tar cigarettes," his vote to raise the titling tax on recreational boats and his vote to raise excise tax on cars "when the bedrock problem was securing for Montgomery County the authority to levey its own gasoline tax to finance Metro."

Keeney also criticized Gilchrist for claiming in his literature that he had "achieved" workable legislation that imposes standards of management on the $1.5 million (state pension) fund." Keeney said that the pension reform bill, though a "needed bill," did not pass this year.

It was there that Gilchrist, when he had his shot, struck back. "It was a $1.5 billion, not million, pension fund." Gilchrist said icily. "And I did sponsoer and pass a bill that put fiduciary management responsibility on people who invest public pension funds." Keeney, Gilchrist said, had belittled the wrong bill.

"I haven't talked about it," Gilchrist went on with a wide grin, "because something about pension legislation tends to empty a room."

In addition, Gilchrist charged, Keeney's tax plan is a "pig in a poke" because it fails to attack what he considers to be the real tax problem.

Then Gilchrist moved to his central campaign theme, that his experience in Annapolis will bring greater perspective and wider state ties to deal more effectively with pressing local problems.

"I shudder to think what would happen to this county if the kind of analysis Mr. Keeney has given you of the state's relationship to the county is applied," Gilchrist said. "Assessments, Metro, education depend significantly on state policies."

"What we really need in this county is new leadership. I think the experience we've had under people like him makes us want that change," Gilchrist said.