Private security guards and former D.C. correction officers began working at the Prince George's county Jail yesterday, filling the positions of 106 guards fired for participating in the five-day strike by county employes.

The six newly hired officers and 10 guards from private security firms replaced state troopers who had been guarding the 440 prisoners in the Upper Marlboro facility since the job action began Tuesday, a jail official reported.

County Executive Lawrence J. Hogan dismissed the striking jail guards immediately after they defied a court order and went on strike at 12:01 a.m. Tuesday. The walkout triggered a four-hour riot by inmates that resulted in $15,000 damage.

The new guards -- who have not been permanently hired, according to a jail spokesman -- include officers recently laid off at Lorton reformatory and employes of two private firms, Burns Detective Agency and Sting Security.

The jail guard issue is one of three major points that still separate county officials and leaders of the five locals of the American Federation of State, County and Municipal Employees.

The union wants the county to take no action against the guards for their participation in the strike. Hogan and county officials insist they will not rehire the guards.

Labor leaders also want union membership to be a condition of employment in union-represented county agencies, a demand that the county rejects. In addition the union demands that strikers be allowed to charge time off the job this week to paid annual leave.

Brian Flores, the federal mediator who called both sides to an eight-hour session Friday ended the meeting after he said the gap between the county and the union was widening.

Hogan said he would meet privately with Flores this morning at an undisclosed location. An aide to Hogan said Hogan would try to "expedite discussion, to see where we go from here."

Meanwhile Rep. Gladys Spellman (D-Md.) attended a rally yesterday for the strikers to express her support. "My heart is with you. I wish for you justice," she said.