The chairman of a Montgomery County panel investigating alleged abuses in a federally funded job-training program accused the county attorney yesterday of thwarting efforts to hire a private investigator and threatened to go to court Monday to stop the county's "obstruction of the investigation."

Fernando Bren, chairman of the Merit System Protection Board, said yesterday, "These actions by the county attorney can only raise additional questions as to the depth and breadth of alleged wrongdoing by high-ranking county officials in the Montgomery County government."

County Attorney Paul A. McGuckian called the accusations untrue. He accused Bren of "going bonkers over this. It's incredible. This guy has gone nuts. He's supposed to be conducting a confidential investigation and he's calling reporters."

The merit board is investigating allegations that federal Comprehensive Employment and Training Act (CETA) funds were misused, that county employes were used to conduct personal business, that federal job training funds were misappropriated, and that CETA employes were unnecessarily laid off because the funds used to pay them were mishandled.

The merit board told the County Council that its probe will go back 14 months, to the time the CETA program was merged in with the Office of Economic Development. Ioanna Morfessis, director of that office, said yesterday, "I have yet to know who my accusers are or what the charges are. I haven't seen any due process in this investigation." As for the allegation of unneeded layoffs, she said funding for the program was reduced from $2.3 million to $550,000 since it was merged under her office.

McGuckian and assistant county attorney Joyce Stern on Friday refused to approve a contract to allow Bren to hire investigator Howard Rosenstein of Baltimore to conduct the CETA probe. Stern, who reviewed the proposed contract late Friday, said she objected to a clause that would have made Rosenstein immune from any court suits during the course of the probe.

Stern, McGuckian and county Chief Administrative Officer Lewis Roberts said it was not county practice to give such immunity to professional, private contractors. But Bren said the contract was identical to a contract Rosenstein negotiated with the county two years ago, when the merit board conducted a probe into alleged hiring abuses in the county liquor department.

County officials are known privately to oppose Rosenstein's selection, since he conducted the investigation two years ago into County Executive Charles W. Gilchrist's administration and the merit board found the merit system had been abused--a finding Gilchrist has disputed.

"The county attorney is in effect trying to put the squeeze on our investigator," Bren said. "This board will not be dictated to by the county attorney."

Bren said "we are prepared to go to court" to ask a judge to force the county to accept the contract with Rosenstein.

Without the contract, two high-ranking county employes described as key witnesses in the investigation backed out of scheduled interviews with Rosenstein on Friday, after conferring with Stern and Roberts.

Bren accused the county officials of advising the two witnesses not to cooperate with Rosenstein. "I find it incredible that the county attorney would have contact with these witnesses," Bren said.

Stern and Roberts said in seperate interviews yesterday that they told the employes the decision whether to talk to the investigator was their own. But both county officials also said they told the employes that Rosenstein did not have a signed contract to conduct the investigation.

"You don't want to talk to someone off the street who says they're the investigator for the board," Stern said. She added that the employes were "big boys and girls with a lot of experience" to make their own decisions.

Roberts, recalling his conversation with one employe, said, "I told the employe that I can't tell you either to talk to him or not to talk to him." Roberts said the employe then asked if Rosenstein was under contract to conduct the probe. "To the best of my knowledge, there is no contract at this time," Roberts said he replied.

Also, without a signed contract, Rosenstein will not be permitted to review the hundreds of documents subpoenaed by the merit board in the probe. Yesterday, county attorneys and CETA officials in Rockville were busy sifting through the reams of financial records, time sheets and computer tapes to determine which should be turned over to the board.