he Robb administration recommended today that nonviolent criminals be released on parole sooner so that the state's crowded prison system can accommodate longer sentences for violent offenders.

Public Safety Secretary Franklin E. White asked the House Courts of Justice Committee to consider a proposal that would make first-time nonviolent offenders eligible for parole after serving one-fifth, rather than one-quarter, of their original sentence.

He requested similar reductions for second- and third-time offenders, which would make them eligible for parole after one-quarter and one-third of their sentences respectively, instead of the current one-third and one-half.

The net effect would be to free up a total of 235 prison beds during the first year of the new program, White said. In all, approximately 2,200 prisoners would be eligible for parole sooner than they are now under existing state law, according to state estimates.

Moving up the parole eligibility date would not mean automatic release for those prisoners since any final decision still would rest in the hands of the state Parole Board, White cautioned later.

White noted that while Virginia ranks 35th in the country in serious crimes, it now ranks 10th in the percentage of its population serving time in prison.

"This is not to say that the situation in Virginia is wrong, only that it is different and that it is costly and that it is going to get more costly," White said.

"I want to satisfy myself that we are only incarcerating, and spending $12,000 to $13,000 a year on, those people who are physically dangerous to the rest of us," he added.

White said he would support a bill that would deny parole to people convicted for the third time of a violent offense. That measure, he said, would increase Virginia's prison population by an estimated 100 inmates in 1989.

Other bills now before the legislature also would affect the state prison system, including a measure backed by Gov. Charles S. Robb and Attorney General Gerald Baliles that would increase the penalty for use of a firearm in the commission of a felony from the present mandatory one year in prison to three years on the first offense. The bill would increase the mandatory sentence for second offenders to five years, up from the current three years.

Corrections official today would not quantify the direct impact of the tougher gun laws, saying only it would be "substantial."

Virginia's prisons are now so crowded that more than 1,000 state prisoners are backed up in local jails, awaiting transfers to state prisons. The state has approximately 10,000 prisoners assigned to its care and that number is expected to increase by 30 percent by 1990.

Two new prisons are scheduled to open this year and, to accommodate the overflow, the state will start putting two prisoners to a cell, increasing the capacity of the two facilities from 1,000 to 1,500.

By reducing the terms for nonviolent offenders, the Robb administration does not expect to affect the anticipated increase in the state's prison population by any substantial degree. "All we would be doing is playing at the edges of the growth," White said today.

White said the state would draw some distinctions within certain types of crimes such as burglary and drug trafficking, which traditionally are regarded as nonviolent. For instance, if a burglar has been convicted of a violent offense anytime within the previous five years, he would not be eligible for the earlier parole eligibility dates reserved for nonviolent offenders.

Virginia several years ago moved to let all prisoners out six months before their release date. The program, criticized by conservatives, was designed to put all exiting inmates under parole supervision.