Interior Secretary James G. Watt has not repaid the Treasury for the private Christmas parties he and his wife threw at Arlington National Cemetery's historic Custis-Lee Mansion.

And Rep. Sidney R. Yates (D-Ill.), chairman of the House Appropriations Committee panel that votes on Interior's budget, is getting tired of waiting for the money.

Yates sent Watt a letter yesterday threatening to cut the full $8,842 cost of the two parties out of his salary unless he pays by Nov. 1.

Interior spokesman Douglas Baldwin declined to comment on the letter, saying he had not seen it. He said Watt has not paid for the parties because Interior officials are still "having conversations" with the General Accounting Office about its conclusion that Watt owes the Treasury $4,300.

This is the third letter Yates has sent Watt about his entertainment tab. The earlier letters, dated Aug. 4 and Sept. 20, simply asked Watt when he planned to send in his check. Yates said Watt has not answered any of the letters.

The GAO ruled that the two parties at the mansion, which is managed by Interior's National Park Service, did not "further official Park Service purposes" and could not be covered by the fund to which Watt billed them.

Watt's official entertainment budget had only $4,500 in it at the time of the GAO's report, leaving the secretary with about $4,300 to pay from his own pocket. Interior asked GAO to reconsider its ruling, and on Aug. 3, the auditors reasserted that the holiday-season functions were personal rather than official.