The nomination of Frederick "Frecky" Vreeland to be U.S. ambassador to Myanmar (Burma) has run into unexpected trouble, congressional and administration sources said yesterday, leaving Senate Foreign Relations Committee members fuming at the State Department.

Vreeland, 63, son of the late Vogue editor, Diana Vreeland, first rankled conservatives who were upset over allegations that, while stationed in the embassy in Rome from 1978 to 1985, Vreeland had tried to play down suspicions that Soviet and Bulgarian agents were involved in a 1981 assassination attempt against Pope John Paul II.

Then, other committee members claimed the administration had submitted Vreeland's nomination with a "cover" biography that listed him as a career Foreign Service officer instead of a career Central Intelligence Agency official, according to administration and committee sources.

Asked about the allegation that Vreeland worked under cover for the CIA, State Department deputy spokesman Richard Boucher said, "We do not comment on any allegations regarding intelligence matters. Ambassador-designate Vreeland has had a distinguished career as a political and economic officer at a number of embassies overseas."

Another State Department official, who declined to be identified, said senior department officials first heard of the concerns over the resume from the committee. But the resume given the committee was "not a subterfuge," the official said, but was "inadvertent at the high levels. It was embarrassing and a mixup," the official said, but "the people on top were not aware" of the resume problem and "the people down below didn't flag it."

Conservatives opposing the nomination cited a 1984 book by journalist Claire Sterling, who was investigating a Soviet-Bulgarian connection to the papal assassination attempt. In her book, Sterling recounted a visit from Vreeland in Rome not long after the assassination attempt in which he said "we have reason to believe that you're on the Bulgarian hit list" and suggested she "cool it for a while . . . Get out of town."

The Senate Foreign Relations Committee, which on Monday considered the nomination in closed session, put off a vote scheduled for Tuesday after a request by Sen. Jesse Helms (R-N.C.). Helms asked that the nomination not be considered, citing a letter he had received from Sen. Alfonse M. D'Amato (R-N.Y.).

In his letter, D'Amato said, "I believe there are serious questions concerning Mr. Vreeland that deserve more thorough examination than was possible at this morning's {Monday's} hearing."

State Department officials said they were confident that Vreeland's nomination would be approved. "I think we have answered D'Amato's concerns," one official said. But D'Amato said "no way" have his concerns been satisfied.

Nominations to Myanmar have rarely sparked controversy. But the political situation there now is tense, with opposition party leaders under house arrest and ruling military officials claiming interference in their nation's affairs by U.S. and other ambassadors.