Virginia Gov. John Dalton, a Republican, yesterday accused Democratic Lt. Gov. Charles S. Robb, who is running for governor, of breaking a confidence for politcal gain by releasing a state police report to the governor. The report said one auto inspection a year instead of two was enough to ensure automobile safety.

Robb had cited the report at a press conference Wednesday when he urged that the inspections be cut to once a year. He said the cutback would be "a very visible symbol" of his determination to reduce state regulations.

But Dalton said that releasing the report "might jeopardize objective analysis" of the issue. "I am disappointed," he said in a statment, "that in this particular instance, political expedience may interfere with a rational review of the data, recommendations and merits of this issue."

An aide to Robb said the lieutenant governor received minutes of the governor's July cabinet meeting, which mentioned the report. But he said Robb learned about the report independently and asked the state police for a copy, which arrived just five minutes before the press conference. The aide, George Stoddart, said the police told Robb that the report was a public document.

Meanwhile, Attorney General Marshall Coleman, Robb's Republican opponent in the governor's race, said he had cosponsored a bill for once-a-year inspections when he was a state senator in 1977. The bill died in committee.