Attorney General Benjamin R. Civiletti said yesterday that a national commission is considering recommending an increase in the nation's yearly immigration quota to 750,000 a figure more than double the current legal limit of 290,000.

Civiletti indicated that the commission also favors an amnesty for millions of illegal aliens who are already here. But he warned that more border guard and tougher law enforcement will be required to win public acceptance of such changes.

The attorney general made his disclosures in a speech to the 51st convention of the League of United Latin American Citizens attended by about 700 delegates from California, Texas and other areas where Hispanics live.

Although the limit on the number of aliens who can be legally admitted in a year is 290,000, Civiletti said emergency programs and special exceptions enabled more than 600,000 to obtain resident alien status last year.

Using this figure, Civiletti said the staff of the national Select Commission on Immigration and Refugee Policy is considering legislation that would allow 750,000 immigrants to enter the United States every year. Such a ceiling would eliminate the 20,000-per-country limit, which Mexican-Americans have attacked.

Of the number proposed, Civiletti said, 359,000 visas would be reserved for immediate relatives of U.S. citizens and permanment resident aliens. An equal number would be available for workers needed here because of economic conditions and shortages of skills.

A quota for 50,000 refugees would be included in the 750,000. In emergencies such as the recent Cuban boatlift, additional numbers of refugees could be admitted by "borrowing" visas from the quota for needed workers.

Civiletti raised two more controversia issues when he spoke of the possible introduction of a national identitiy card and penalities on employers who knowingly hire illegal aliens. Civil rights advocates have opposed the penalty on employers on grounds that some might refuse to hire Hispanics in order to avoid penalties or would ask only Hispanics for proof of legal status.

A national work permit that all workers would have to show could resolve the problem without discrimination, he said.

Civiletti is one of the 16 members of the Select Commission on Immigration and Refugee Policy.

The commission, headed by the Rev. Theodore Hesburgh, is expected to present its recommendations for immigration reform at the end of this year.