Interior Secretary James G. Watt feted himself, his wife and about 200 guests at two unofficial holiday season parties held at historic Arlington House, the publicly owned and operated home of Robert E. Lee.

One of the parties, a breakfast hosted by Watt's wife, Leilani, on Dec. 14, kept the house closed almost two hours past public opening time. Some critics said that move violated a National Park Service guideline which stipulates that Arlington House--or Custis-Lee Mansion, as it is also known--may not be closed to the public during regularly scheduled hours in order to accommodate social functions.

Watt aides said they could not reach the secretary for comment yesterday. Interior Department spokesman Douglas Baldwin said the breakfast and a large cocktail party held three days later were attended by "senior White House officials and cabinet personnel," although he and several other Interior spokesmen said they were unable to determine the names of any of those attending. The office of presidential counselor Edwin Meese III said yesterday that his schedule showed he attended the cocktail party.

President Reagan and Vice President Bush were invited to the cocktail party but were not able to attend, according to Interior Department spokesman Harmon Kallman. Baldwin said the parties were not official Interior Department functions and that there were "ample precedents around town" for them.

Baldwin said Watt's decision to hold the parties at the mansion rather than at the Interior Department came from a "desire to have a place where people could be served liquor. The secretary didn't feel it was appropriate to have liquor served in a government building," Baldwin said. Also, Baldwin added, "the facility is quite nice."

The large yellow mansion sits atop a hill in the middle of Arlington National Cemetery and is visible to motorists heading toward Virginia on the Memorial Bridge. Baldwin said the parties made use of the mansion's White Parlor and central hallway.

He said he had no idea how much the parties cost, and said he would not know until the bills came in. The parties were paid for out of a National Park Service "voluntary donation fund" and did not involve appropriated government funds, Baldwin said.

Interior spokesman Thomas DeRocco said the fund, which is about 15 years old, consists of donations from private citizens and corporations. It is available to the secretary, who is accountable to Congress for its use. He added that he was certain no public visitors appeared at the house the morning of the breakfast until after the house reopened at 11 a.m.

At the evening cocktail party, the metal barriers blocking doorways to Arlington House's refurbished rooms were taken down and replaced with red ribbon, said a volunteer guide who was there, but who asked not to be named. At both parties staff and volunteer guides were asked to be on hand, the guides in historic costume.

The catered cocktail party attracted between 150 and 200 guests and the breakfast about 20 guests, Baldwin said. Several people in attendance said that at the cocktail party a large tent was set up outside the house where drinks and hors d'oeuvres were served.

One volunteer, Elizabeth R. Shearer, a 70-year-old Arlington resident who has been a guide at the house for 10 years, was so incensed at Watt's use of the public house and staff that she fired off a two-page letter to him on Dec. 19: "The public should know that Interior Secretary James Watt and Mrs. Watt have put to private use a national memorial for which he is the public trustee," Shearer wrote.

"There were at least five park service trucks there helping," Shearer said Arlington House volunteers later told her. She added that another guide who attended the cocktail party told Shearer she had overheard Watt greet guests by saying, "Mr. Reagan has the White House, I have Arlington House ." Baldwin said that while Interior staffers attended, "they were not paid." National Park Service Site supervisor Ann Fuqua and curator Agnes Mullins declined to comment on the parties.

The normal paid staff at the mansion is nine people. The house receives approximately 450,000 visitors annually, and its winter hours are 9:30 a.m. to 4:30 p.m. daily. The house is occasionally opened to the public during the evening for candlelight tours. It is such delicate condition that there is a weight limit on the second floor.

Prior to 1971 the home had never been used for social occasions, but from 1971 to 1975 parties and receptions there became routine, said Park Service spokesman George Berklacy. The practice was controversial, however, and was curtailed drastically in 1975 when a policy panel issued guidelines which restricted the use of the house.

"Everyone I talked to, from staff to volunteers, felt the same way I did," a still-angry Shearer said. "I just do not see a national memorial being used as a private club. Arlington House has a beautiful view of the city. It's a beautiful place to pull up a limousine."