Arab-American leaders told the U.S. Commission on Civil Rights yesterday that they and their communities have been subjected to widespread discrimination, harassment and violence and requested a formal investigation.

The group also charged that the Federal Bureau of Investigation has been reluctant to investigate violence against Arab Americans and has conducted surveillance against Arab-American political activists.

Oliver (Buck) Revell, the FBI's executive assistant director for investigations, denied the charges and told the commission that one of the FBI's "highest priorities" is its investigation into the bombing murder in Los Angeles last year of Alex Odeh, an Arab-American leader. Revell said the FBI does not hesitate to pursue domestic terrorists wherever "they fall on the political spectrum."

Wallace P. Warfield, associate director of the Justice Department's Community Relations Service, said work has begun in some parts of the country to attempt to ease tensions between Arab Americans and their neighbors.

Former senator James Abourezk (D-S.D.), who heads the Arab American Anti-Discrimination Committee (ADC), said, "Arab Americans have become scapegoats for tensions and violence half a world away . . . . "

Abourezk said the problems have been exacerbated by President Reagan, who, he said, has "created a cowboy anti-Arab atmosphere" with his statements on terrorism.

Odeh's widow, Norma, complained to the commission about lack of public outcry over her husband's death. "While the families of terror's other victims received personal condolences, we heard not a word," she said. Sami Odeh, the victim's brother, said in a written statement that the family received a fund-raising letter from Reagan "thanking Alex for past campaign contributions and asking for more in the future."

Revell said he believes that "Arab Americans are at risk" and have been targeted for violence. "That is despicable," he said, adding that Abourezk and James J. Zogby, director of the Arab-American Institute, probably risk being attacked because of their high profile on issues involving Arab Americans.

Abourezk and Zogby blamed some major Jewish groups, including the Anti-Defamation League of B'nai B'rith, as well as politicians and the news and entertainment media for encouraging anti-Arab stereotypes and portraying all terrorists as Arabs.

Abourezk told the commission that the Arab-Israeli conflict and the 1970s oil embargo "have given rise to an ugly, racist type of anti-Semitism toward people of Arab descent living in this country."