A federal judge yesterday approved a search of former president Nixon's private files in a government attempt to determine the location of possibly missing expensive foreign gifts.

At the same time however, U.S. District Court Judge Aubrey E. Robinson Jr. expressed reservations about the procedure under which future searches will be made and suggested the government improve its regulations governing such searches.

The search through the foreign gift inventory contained in the impounded Nixon files will be the first made in them other than for national security reasons or legal proceedings.

Nixon, or a person designated by him, can attend the search and raise objections if he believes an paper to be personal and private rather than a valid presidential historical document. The search probably will occur within a week or so, according to government attorneys.

The search was requested by U.S. Protocol Chief Evan Dobelle after questions were raised about the location of certain gifts the Nixon family received from foreign countries.

Nixon's attorneys won a temporary order about one month ago from another judge who blocked the search until Robinson, who has heard other aspects of the Nixon papers cases, could hear the arguments.

Although questioning the government's regulations, Robinson agreed after a two-hour court hearing yesterday to allow this particular search.

The judge said the government should make sure its regulations "insure there is minimal intrusion" on Nixon's privacy when such searches are made and that the regulations provide guidelines for the General Services Administration to follow when such searches are conducted.

The specific box of documents to be searched is reported to contain photographs and lists of foreign gifts. U.S. law requires officials, including presidents, to turn over to the State Department's gift unit any foreign gifts worth more than $50.

The Washington Post reported on Monday that while some of the gifts may be unaccounted for because of sloppy records, State Department and GSA officials say some gifts are believed to be in the custody of the Nixons.