The Montgomery County Council yesterday passed legislation giving the county and its housing agency right of first refusal to purchase rental apartment buildings that are proposed for condominium conversion.

Passed unanimously, the bill is designed to supersede stronger tenant protection measures that many county officials believe conflict with state law and therefore will be struck down in court.

The county government hopes that yesterday's vote will conclude the county's long and troubled efforts to regulate a wave of condominium conversions that began in the late 1970s. County Executive Charles W. Gilchrist has said that about a quarter of the county's rental units that existed 12 years ago had been converted to condominiums as of the beginning of this year.

If Gilchrist signs into law the measure and two others designed to augment it, as he is expected to do, they will go into effect July 1.

The new law would not grant refusal rights to tenants' associations as the current law does. State enabling legislation passed in Annapolis earlier this year specifically denies tenant groups that right.

If the county did not purchase a particular building, the new law would grant the county rights to purchase certain units in the building and require that up to 20 percent of the units be retained on the rental market.

Certain senior and handicapped citizens would be eligible for lifetime tenancies, while others of that group, and tenants meeting certain income guidelines, could apply for three-year extensions on their leases.

The council also approved legislation yesterday limiting rent increases to one per year and requiring 60-day notice to tenants. A third bill passed would broaden eligibility for aid from county funds created to assist tenants displaced by condo conversion.

The District of Columbia's condominium regulations will continue to be the most stringent in the area. Key provisions took effect last September that provide extended tenancies, moving expenses, a secret ballot vote by tenants on the conversion of a building and a conversion fee to be paid by the developer. Tenants who are 62 years old or over and whose annual income is less than $30,000 have the right to remain tenants for the life of the law, which expires in three years unless renewed.

Prince George's County, which has not had as many condominium conversions as the rest of the Washington area, does not regulate conversions.

Northern Virginia jurisdictions are under a state law that requires a 120-day notice of conversion and gives tenants first option to buy individual apartments during the first 60 days. There are no extended tenancies or moving expenses, although the local governments can pass guidelines asking developers for voluntary cooperation. Arlington, for example, requests developers to pay $340 in moving expenses for the occupants of a one-bedroom apartment, and $380 for a two-bedroom apartment.

In Maryland, Montgomery County has led a two-year fight for regulation of condominiums.

Earlier this year, after a setback in court, Gilchrist, senior citizen groups and county lobbyists went to Annapolis to push for new state legislation giving local jurisdictions right to regulate as they saw fit.

A compromise state law emerged from the fight giving refusal rights to county governments and their housing agencies (in Montgomery's case, the Housing Opportunities Commission) but denying it to tenants' associations, as developers wanted.

The bills approved yesterday were designed to implement the new state program. During hearings, council member Rose Crenca said financial limitations would prevent the county from purchasing buildings, making the bill meaningless. Amendments she introduced to restore tenants' rights were not passed.

Blair Lee IV, the county's lobbyist in Annapolis, said the intention was for the county to own the buildings only briefly before reselling them to tenant or other groups, which would retain them on the rental market.

In other business yesterday, the council set the general real estate tax rate at $2.27 per $100 of assessed valuation, as expected. The new rate is seven cents lower than the previous one, but will still mean higher taxes for about two-thirds of county home-owners.

The council also overrode about $240,000 of Gilchrist's budget vetoes, bringing the total of such restorations to about a half million dollars. Yesterday's restorations included $100,000 for elevator inspection services, $56,000 for a well- and ground water-testing laboratory, $20,000 for recreation department outreach programs and $65,000 for Housing Opportunities Commission operations.