More than half of the 1,264 medium-security inmates at the Lorton Reformatory refused to work or attend classes yesterday, the fourth day of protests by inmates objecting to increased security searches of visitors.

Corrections spokesman Leory Anderson said work in the industriral and culinary units of the prison was disrupted, but no serious incidents were reported. "Things, relatively speaking, are back to normal," Anderson said. He said as many as 80 percent of the inmates stayed away from work assignments Monday, but officals noted that the protest was during a holiday weekend when less work than ususal is done.

Prison officials met with about 100 of the inmates late yesterday and said no changes would be made in the search procedures but supervisors would monitor more closely the guards who conduct the searches. The officials said they expected the protest to end today.

Inmates and some visitors have complained that some of the guards violated the privacy of visitors with excessive frisking, although no one was strip-searched.

Salanda V. Whitfield, administrator of medium-security inmates at the Central facility, said the protests followed an increase during the last few weeks in the amount of contraband seized from persons trying to smuggle drugs and alcohol into the prison.

Prison officials said the contraband usually is small amounts of marijuana or illegal pills, but said one woman was arrested last week after guards discovered she was carrying more than 250 pills.

Correctional officers inside Lorton said yesterday that the illegal pills, usually amphetamines, sell for $15 each or two for $25 within the prison, while an ounce of marijuana can be broken down into individual cigarettes and sold for a total of $80.

"They [the inmates] said the searches were dehumanizing," an official said. "They don't like it because we're catching so much stuff."