About 70 inmates in the maximum security section of Lorton Reformatory took over a prison mess hall for about seven hours yesterday in protest of a new regulation designed to curb suspected homosexual activity and drug trafficking.

D.C. Correction Department spokesman LeRoy Anderson said the demonstration ended about 7 p.m. with all of the inmates back in their cells. There were no injuries reported in the incident, but Anderson said the inmates "just wrecked" the mess hall.

Two of five knives discovered missing from kitchen supplies after the incident were recovered early last evening, Anderson said. A search for the other three was continuing last night.

Anderson said the protest was sparked by implementation Tuesday of a new procedure under which inmates who chose not to take part in recreation periods must remain in remain in locked cells. Previously inmates who remained in cell blocks during exercise periods had been allowed to exchange visits in their cells.

Prison officials met briefly with several of the demonstrating inmates but refused to modify the new regulation, Anderson said.

Anderson said the demonstration began about noon after a group of 40 inmates who refused to leave an exercise yard were joined by 30 others on the way to the mess hall. The men then forced their way into the mess hall, he said.