The Defense Department and Central Intelligence Agency are urging the White House to approve -- before the U.S.-Soviet summit -- a large covert military operation to aid noncommunist rebels fighting the Marxist Angolan government, congressional and intelligence sources said yesterday.

One source said the money proposed is in the range of "two to three hundred million dollars," a figure eight to 10 times higher than any proposed aid packages for Angolan rebels being considered by Congress.

Top Pentagon officials reportedly are particularly anxious to have the administration reach a decision before the Nov. 19-20 summit in order to strengthen President Reagan's hand in any negotiations with Soviet leader Mikhail Gorbachev about regional conflicts in which the two superpowers are engaged.

Whether the United States should become reinvolved in the Angolan conflict by providing assistance to the Union for the Total Independence of Angola (UNITA), which the CIA aided during the 1975-76 civil war there, has created sharp internal divisions in various agencies and departments. Congress appears just as divided.

Meanwhile, the administration was reported yesterday to have given "private assurances" to House Rules Committee Chairman Claude Pepper (D-Fla.) that it will back the bill he is cosponsoring with Rep. Jack Kemp (R-N.Y.) to provide $27 million in nonlethal aid to UNITA, led by Jonas Savimbi.

A Pepper aide said administration officials, who he said asked not to be identified, had given these assurances "very recently" and announcement of the decision is "a question of timing."

If true, this would represent a major policy shift over the last three weeks. On Oct. 12, Secretary of State George P. Shultz wrote House Minority Leader Robert H. Michel (R-Ill.), saying the administration thinks the Pepper-Kemp bill is "ill-timed" and urging him to oppose it.

Various proposals to provide UNITA with aid -- either covert or overt and humanitarian or military -- have been discussed within the administration and Congress for a month, with some principal policy-makers shifting positions on the issue.

CIA Director William J. Casey recently switched from supporting only humanitarian aid to favoring a covert military program, according to one source in the intelligence committee.

The sharp controversy emerged clearly yesterday during testimony before the House Foreign Affairs subcommittee on Africa.

Rep. Mark D. Siljander (R-Mich.) introduced with 41 co-sponsors a proposal to provide $27 million in overt military aid to UNITA, saying U.S. ambivalence toward the Angolan conflict has helped prolong "Cuban and Soviet occupation" of that country.

Subcommittee Chairman Howard E. Wolpe (D-Mich.) said he strongly opposes U.S. intervention of any kind, saying, "There is probably no better way to play into the hands of the Soviets and Cubans."

Wolpe predicted that U.S. aid to UNITA would increase Angolan government dependence on Cuba and the Soviet Union, allow the Soviets to discredit the United States in black Africa as an ally of white-ruled South Africa, and lead to U.S. aid to Savimbi, whom he described as an "avowed Marxist" and a "Maoist."

Also arguing strongly against renewed U.S. involvement in Angola was David D. Newsom, a former U.S. ambassador to several nations and assistant secretary of state for African affairs during the Nixon adminstration.

Newsom questioned whether there is a sufficient public consensus to sustain a prolonged U.S. commitment to Savimbi.