Campaigners for Virginia Democratic gubernatorial candidate Charles S. Robb yesterday began a radio advertising effort charging that Republican opponent J. Marshall Coleman condones the use of public office for the personal gain of his political allies.

Coleman "is caught in a web of scandal," one commercial begins. He "seems to be blind to conflicts of interest when they affect his interest or that of his friends. Maybe that's what Coleman means with his slogan, 'Keep a Good Thing Going.' "

A similar commercial, scheduled to be aired around the state beginning today, adds that "Coleman is saying it's okay for a public official to fatten his wallet and that of his clients at the expense of the public."

The ads refer to recent reports that Coleman's running mate, State Sen. Nathan Miller, introduced and helped secure passage of legislation that could make it easier for one of his law firm's clients to win potentially lucrative mineral rights. They also tie Coleman, Virginia's attorney general, to William B. Wrench, a Coleman fundraiser who earlier resigned from the state highway commission after it was reported that he owned property near a proposed route for the Springfield Bypass for which he had voted.

Coleman press aide David Blee called the ads "absolute misrepresentation. Anybody who knows Marshall Coleman knows he has been a proponent for a more ethical government . . . I think this gutter strategy will backfire."

On Thursday, as copies of the radio ads were being mailed to stations from Washington to Norfolk, Robb told reporters that any investigation of Miller's conduct by the legislature should be delayed until after the Nov. 3 election "so that elements of partisanship don't cloud the merits."

"I support Mr. Miller," Coleman said yesterday in Alexandria, though he has declined to comment further. "I'm not sufficiently conversant to make a judgment," he has said.

Wrench resigned from his highway commission post one day after Coleman issued a report saying Wrench had violated the spirit of Virginia's conflict of interest law. Even so, Robb spokesman George Stoddart said yesterday, "it's obviously inappropriate for an attorney general to investigate one of his own fund-raisers. How is it possible for somebody to fairly and impartially investigate someone who's paying part of his salary?"

Coleman is drawing half his salary from the attorney general's office and half from campaign funds while he runs for governor.

Republicans have responded to Democratic attacks this week by airing a television commercial portraying Coleman, Miller and attorney general candidate Wyatt Durette as victims of mudslinging. "Some politicians believe to win elections you have to throw mud," says an announcer, as mud is hurled at a campaign poster of the three candidates.

GOP radio commercials attack Robb's economic proposals as "The Great Society . . . Robb's Virginia version." They predict that a Robb victory would lead to "more and higher taxes for me, for you."