WASHINGTON--Fawn Hall testified yesterday she spirited secret documents from the White House when the Iran-Contra connection was revealed because she feared they would fall into the wrong hands.

"It wasn't the KGB that was coming, Miss Hall, it was the FBI," countered Sen. Warren B. Rudman (R-N.H.).

"That's true, sir, but we do in this country have a tendency to have classified documents get on the front page of The New York Times," said the witness.

Hall, who was Lt. Col. Oliver North's secretary at the National Security Council, was the 18th witness as the joint House and Senate committees ended the first phase of their public hearings and adjourned for two weeks.

"What these committees have heard is a depressing story," said Rep. Lee Hamilton (D-Ind.), chairman of the House committee. "It is a story of not telling the truth to the Congress and the American people," he said, ticking off a litany of the affair in which he said a secret supply network was established to aid the Contra rebels, arms were sold covertly to Iran and some administration officials made efforts to mislead Congress about their activities.

Hall said she didn't consider her activities of shredding, altering or removing sensitive documents from North's office to be part of a cover-up. "I use the word protect," she said.

At one point during her second day of questioning at the televised hearings, Hall said her activity was justified because "sometimes you have to go above the written law."

But a few minutes later, she retracted the statement. "I don't feel that," she said.

In the second phase, the committees expect to hear from the two central figures identified in the case so far--North, who was a National Security Council aide, and his former boss, Rear Adm. John Poindexter. If the two men testify, it will be under limited grants of immunity from prosecution.

In nearly six weeks of hearings, the committees received what Hamilton described as "some of the most extraordinary testimony ever given to the U.S. Congress."

"Our government cannot function cloaked in secrecy," said Hamilton. "It cannot function unless officials tell the truth. The Constitution only works when the two branches of government trust one another and cooperate."

After the session, Rudman said, "I have never believed that Col. North acted alone, acted without direction. I don't think the President's role can ever be measured until North and Poindexter are heard from."

Hall was led again through her activities on November 21, 1986, just before Justice Department investigators were to search North's White House office for documents.

An administration supporter, Sen. Orrin Hatch (R-Utah), brought out in his questioning Hall's contention that she shredded, altered and sneaked out documents in her clothes because she felt the lives of American hostages in Lebanon were involved.

"With respect to the shredding and the other activities, which I have to admit do not look very good," Hatch began, joining in the laughter that followed. "Do you feel...that regardless of how bad they might look, do you think that we should hear Col. North's explanations for those actions before we draw any final conclusions?"

Said Hall: "It would be fair to Col. North, yes."

That brought a rejoinder later from Rudman that "Col. North's not being here to answer these charges is his choice, not ours."

North has invoked his constitutional right not to testify because he might incriminate himself, and the congressional committees have voted to grant him limited immunity in order to compel his testimony.