Eight Democratic members of the House Permanent Select Committee on Intelligence introduced a bill yesterday to stop the Reagan administration's plan to give covert military aid to Angolan rebel leader Jonas Savimbi.

The bill, authored by Rep. Lee H. Hamilton (D-Ind.), committee chairman, would allow aid to Savimbi "only if the provision of that support is the openly acknowledged policy of the United States" and is approved by a joint resolution of Congress.

The Democratic challenge to U.S. covert involvement in Angola, approved by the president in November, coincides with what is expected to be a strong Democratic-led drive to block the administration's request for $70 million for a much larger covert operation to aid anticommunist forces in Nicaragua.

The Hamilton bill says that the United States "should not provide any such support until the president has publicly informed the Congress and the American people that United States government support for military or paramilitary operations in Angola is important to the national security and the Congress has approved such support."

Congressional approval of covert operations is not required, but Congress has occasionally stopped such activity by special legislation.

The Hamilton bill follows Savimbi's 10-day, high-profile visit to Washington earlier this month during which President Reagan and Secretary of State George P. Shultz said that the administration is committed to giving Savimbi "effective" military aid. Savimbi has said he needs U.S. military aid immediately to stave off an expected Cuban-backed offensive in April or May.

U.S. aid to Savimbi through the Central Intelligence Agency was cut off 10 years ago by the Clark Amendment. The amendment was repealed in July, clearing the way for congressional conservatives to press for renewal of assistance to Savimbi's National Union for the Total Liberation of Angola, UNITA.

The Hamilton bill could force the first test of congressional will on Marxist-ruled Angola. Over the past several months, efforts by House members to either support or block aid to Savimbi have gathered a little more than 100 signatures each, leaving more than 200 members undecided.

The legislation will be referred to the House intelligence panel, which is planning a public hearing March 13 and a drafting session March 18.

If passed by both the House and Senate, which remains uncertain, the legislation would also allow Congress to keep control of the flow of aid to Savimbi, now set at an initial $10 million to $15 million.

A State Department spokesman said yesterday that the bill has not been studied, but he added that the administration has expressed its strong opposition to congressional contraints on the president's ability to conduct foreign policy.