A legislative aide to Northern Virginia Rep. Frank R. Wolf has been placed on leave after his arrest on charges of attacking the son of his next door neighbor with a five-inch meat cleaver on Christmas night.

Sewall K. Hoff, 39, who has served on Wolf's staff for two years and worked on some of his political campaigns, called Wolf and asked to be placed on administrative leave on Sunday, a Wolf aide said yesterday.

"It is our understanding that he acted in self-defense," said Stephanie Bolick, Wolf's administrative assistant. "He was afraid for his wife and his family."

Hoff, was charged with malicious wounding in the attack, which allegedly occurred at 11:57 p.m. Saturday in the aide's home in the 2500 block of Cavendish Drive in Fairfax County, according to a police report. The alleged victim, Richard Andrews, 32, said yesterday that he suffered a skull fracture and a 5 1/2-inch gash on his head and was "bleeding profusely" after the attack.

"I was saying good night and he hit me in the head with a meat cleaver," said Andrews. "As far as I know it was a totally unprovoked attack."

Hoff refused to talk to a reporter yesterday, but his lawyer, T. Farrell Egge, offered a different account.

Hoff and his wife "were spending a quiet Christmas evening at home" when Andrews visited them uninvited, Egge said. Andrews remained for about an hour "but there wasn't any way of getting him out of the house and things deteriorated," he said.

Egge also said that Hoff had never before met Andrews, although his wife knew him as the son of their next door neighbor.

"I had been drinking beer and had one shot of tequila with Mr. Hoff," said Andrews. "Mr. Hoff had quite a bit more than that."

Bolick described Hoff yesterday as a "good campaign worker and a faithful employe," and declined further comment. "The congressman feels that is a private matter and a personal tragedy for Mr. Hoff."