Vice President Bush was interviewed under oath for several hours yesterday by lawyers for the independent counsel who asked about Bush's contacts with former national security adviser John M. Poindexter and National Security Council staff member Lt. Col. Oliver L. North and what Bush knew of the authority they had for actions in the Iran-contra affair, according to informed sources.

Bush was questioned by prosecutors working for Lawrence E. Walsh who are probing the activities of North and Poindexter in the secret Iran arms sales and establishment of the private network to support the Nicaraguan contras, the sources said. Bush may be called as a witness if North and Poindexter are indicted and tried, the sources said.

A spokesman for Bush, Stephen Hart, said Bush voluntarily met with Walsh's attorneys and "answered all questions posed by members of the independent counsel's staff. All questions were answered completely, fully and under oath." Hart said the independent counsel's office "once again emphasized" that Bush "is merely a witness and is not under investigation by the independent counsel."

Hart would not comment on any details of the interview, conducted in Bush's office in the Old Executive Office Building.

However, sources said Bush opened the session by complaining to the lawyers for Walsh about the advance media billing and the attention his planned appearance had generated. Before starting the sworn testimony, Bush said he was disturbed at what he implied were statements or leaks from Walsh's office about his appearance.

The interview with Walsh comes as Bush is locked in an increasingly hard-fought battle with Senate Minority Leader Robert J. Dole (R-Kan.) for the Republican presidential nomination. Dole has demanded that Bush disclose all information about his role in the affair and the advice he gave President Reagan. Bush has vowed to keep the advice to Reagan private, saying he supported the president but had "reservations" and did not hear the objections of senior Cabinet members to the Iran arms sales.

In another aspect of the political contest, Bush has called for Dole and others to make public their tax returns for the last 10 years, and last night Bush released copies of his returns between 1973 and 1986, a number of which had been released earlier. In 1986, Bush paid taxes of $115,486 on an adjusted gross income of $346,344.

Asked yesterday when he would comply with Bush's demand, Dole said, "I'll make that decision."

Although Dole's tax returns are not public, separate financial disclosure statements filed last year by Dole and his wife, former Transportation Secretary Elizabeth Hanford Dole, shed some light on their income. Dole had outside income of $135,543 in 1986 in addition to his Senate salary of $85,000, and he received between $10,100 and $31,000 in interest, dividends and rent, according to the report he filed last May.

His wife, in a report required in her capacity as a Cabinet member, last October reported annual income of $50,000 to $100,000 from a blind trust set up in 1985. Her annual salary was $99,500 when she resigned the post last year to work on her husband's campaign. Elizabeth Dole also kept $22,050 from speeches and articles in 1987.

Bush's interview with lawyers for Walsh yesterday came after "substantial" negotiations over the ground rules, sources said. Reagan has answered written questions from Walsh but so far not been interviewed by the prosecutors.

A spokesman for Walsh said last night he could not comment on any aspect of the Bush interview.

North and Poindexter are targets in the probe of the arms sales to Iran and the secret network set up to aid the contras.

Bush has said he did not know that money from the Iran arms deals was being diverted to the contras.

Bush invited both North and Poindexter to his Christmas party last month. He has also been a strong public defender of North. As recently as Saturday, in a campaign appearance in Madison, Wis., Bush described North as a patriot who suffered combat injuries in Vietnam while others were "tearing up the American flag."

Bush also said North "risked his life" by accompanying former national security adviser Robert C. McFarlane to Tehran in May 1986 on a mission to seek release of American hostages held in Lebanon and delivering arms to Iranians.

Bush also denied that North had violated the Boland Amendment against direct U.S. military aid to the contras. "The Boland Amendment was not violated," he said. "Don't believe it when you hear that allegation from the liberal Democrats that it was violated. It was not."

Staff writer Dan Morgan contributed to this report.