Officials of the state Department of Public Safety will announcing today whether they will issue a permanent certificate of occupancy for a jail located on the 17th through 20th floors of the Middlesex Country Courthouse building in East Cambridge.

The state panel has the authority to overrule the Cambridge building commissioner's recent denial of a permit to allow the Middlesex County sheriff to house prisoners in the jail. The commissioner called the jail a fire hazard because it lacks a sprinkler system.

County officials began housing prisoners at the Cambridge jail two weeks ago for the first time since its completion in 1974, after nearby jails became overcrowded

Later in the month, a superior court judge will determine the jail's future when he considers the county's appeal of a ruling last week that the jail is too unsafe to house prisoners Today's decision will have a great influence on the appeal, officials agree

About 37 prisoners remain in the jail because a judge ruled last week that the jail can stay in use until the appeal is decided.

After a day long hearing before the three member panel yesterday. William J. Gustus counsel for Middlesex County, said he was confident that the certificate of occupancy would be issued. The chief point of contention in the decision is whether the jail in subject to a 1975 state code requiring sprinkler system in certain buildings. Gustus said, adding that a statue exempts buildings constructed before 1975 from the requirement.

But Cambridge City Solicitor Russell B. Higley said yesterday that the sprinkler requirement does apply to the jail because it was not occupied until after 1975, even though the building's lower floors have been in use since 1974 The code refers to a lot's date of occupancy and not its date of construction, Higley said

Cambridge Fire Department Chief Daniel J. Reagan said yesterday that because the same panel has already overruled city officials by issuing a temporary occupancy permit last week, issuance of a permanent permit is likely

But he added, "I'm continuing to insist that the jail as a fire hazard"

The chief security officer for the jail said yesterday that the risk of a fire is very low because of a recently implemented 24 hour fire-watch.

Peter Vellucci, a member of the East Cambridge Citizen's Planning Team, which is leading opposition to the jail, said his group plans to meet tonight to discuss strategies for keeping the jail unoccupied.