The Reagan administration was attacked bitterly by blacks and other civil rights advocates yesterday as a Senate Judiciary subcommittee began hearings on extension of the 1965 Voting Rights Act.

Benjamin Hooks, executive director of the NAACP and chairman of the Leadership Conference on Civil Rights and the Black Leadership Forum, testified that he could not point to "any action of this administration that would give any hope of comfort to minorities."

The administration is backing what civil rights groups say would be a crippling amendment to the House-passed version of the voting bill. It would make state and local electoral procedures illegal only if they could be shown to be discriminatory in intent, and not simply in effect.

In an interview last night with CBS News, President Reagan reiterated his desire for extension of the act, and said, "I believe I can support the House version . . . . I don't know of anything in it that would justify a veto."

Hooks said the administration position "signals black people that civil rights is not a high priority. We have agitated, we have lobbied . . . talked to the president, the vice president, members of the Cabinet. It is the main item on the agenda of black America . . . . They listen but don't hear."

Sen. Edward M. Kennedy (D-Mass.) said to Attorney General William French Smith, "You appear before this committee when there is a serious crisis of confidence in this administration, in its commitment to many millions of people in this country, most of whom are women and minorities whose skins are not white."

Citing the recent administration decision to give tax-exempt status to some private schools that discriminate, Kennedy asked, "How can a significant group of Americans whose skin is not white, let alone the majority of Americans who care deeply, have much confidence in your attitude on voting rights?"

Smith, bristling, retorted, "The president does not have a discriminatory bone in his body."

Chairman Orrin G. Hatch (R-Utah) threatened to clear the hearing room when the audience, made up largely of civil rights advocates waiting to testify, erupted in hisses and laughter. "We're going to show respect for Smith and the president of the United States who, I know, does not have a discriminatory bone in his body," Hatch said.

Both sides in the dispute agree the key sections of the voting rights law should be extended when it expires in August, but there are sharp differences over the intent test and a number of other provisions.

Smith called the Voting Rights Act the centerpiece of legal protections against infringements on minority voting power, and said that, despite its success in producing registration of millions of black and other minority-group members, "The sad truth is that racial discrimination in the electoral process still exists in certain . . . jurisdictions."

But Smith held out for the intent standard rather than the effect criterion approved overwhelmingly by the House last October on a 389-to-24 vote. Civil rights groups say an intent standard would make it tougher, and in some cases impossible, to prove voting rights violations. A group of 62 senators, large enough to guarantee passage and end a filibuster, has joined in co-sponsoring the House bill in the Senate.

But intent proponents say the House standard could destroy the American political structure.

Smith said, "Quotas would be the end result . . . . The only ultimate logical result would be proportional representation. I don't see how anyone could seriously advocate that."

Hatch warned that two-thirds of the municipal governments in the country have an at-large election system that could be interpreted as harmful to minority representation.

Sponsors of that bill repeatedly asked Smith how lawyers can prove intent, especially in cases dating back to the early 1900s in which local officials may have been dead for years.

Sen. Charles McC. Mathias Jr. (R-Md.), a former city attorney, said, "Any city or attorney worth his salt is not going to allow his mayor or his city council to be caught with the intent to discriminate."

Sen. Howard M. Metzenbaum (D-Ohio) said, "You know and I know, as former practicing lawyers, that proving intent is so unbelieveably difficult. I have difficulty understanding why the administration is not on the side of the overwhelming majority of the House and the overwhelming majority of the Senate on this issue."

Smith replied, "The easy thing to do would be to do exactly what you are proposing. It would be the popular, happy thing to do. But I think our function should be more than that."

The administration also objects to a House provision that would extend indefinitely a portion of the Voting Rights Act that required nine states and parts of 13 others to obtain federal approval for any voting law changes because of past discriminatory practices. The administration would like that extended 10 years.

Both sides are recommending a "bailout" provision to allow states and local jurisdictions falling under that category to be freed from the requirements after a certain number of years of good behavior.