WASHINGTON (AP) _ The Rev. Theodore M. Hesburgh, president of Notre Dame University, said Monday that any immigration bill passed by Congress must include employer sanctions and a reliable identification card.

Hesburgh told Congress that a combined penalty and verification system would not increase discrimination against Hispanics, calling such a contention ''the most flimsy argument you find in this whole area.''

The educator, clergyman and former chairman of a commission that studied immigration reform testified before the Senate Judiciary Committee's immigration subcommittee. The panel's chairman, Alan K. Simpson, R-Wyo., asked Hesburgh and other witnesses to comment on his latest immigration bill, introduced in May.

Hesburgh's view was challenged by Wade Henderson, legislative counsel for the American Civil Liberties Union, who said sanctions ''would lead to discrimination'' and a new identification card ''would have serious civil liberties problems.''

Simpson was co-sponsor of the major immigration bill before Congress last year, which died in conference at the end of the session. His latest bill provides for stiff fines for employers hiring undocumented workers, and delays any amnesty program until a presiddential commission concludes the sanctions are working.

Initially, the bill would permit employers to use existing documents such as passports, birth certificates or driver's licenses to verify that job applicants are legal residents.

As a safeguard, changes could be made only if a president gave advance notice to Congress - two years in the case of major changes.

Hesburgh said employer sanctions are necessary because illegal immigrants cross U.S. borders mainly for jobs. He recalled that a witness told his immigration commission that by working four days in the United States, he could earn the equivalent of a month's pay in his native village - where there was no work, anyway. He did not identify the man's native country.

Hesburgh suggested that legal immigrants could apply for a modified Social Security card that would be ''at least as secure as your credit card.'' He added, ''Without an easily verifiable identification system, employer sanctions won't work.''

Scoffing at reports that such a card would invade privacy, Hesburgh said that when computers were invented, ''Privacy went out the window.''

Henderson testified the ACLU does not oppose continued use of existing documents for verification of status, but opposes new documents.

He said it would be impossible to devise a Social Security card for immigrants because all current Social Security information in government computers would have to be checked and verified. He said the General Accounting Office has studied the proposal and found it unworkable.

Henderson said all sides should take a fresh approach to immigration reform, but Simpson pointed out five presidents and four commissions already have done so.