Herbert Brownell, attorney general during the Eisenhower administration, testified yesterday in federal court here that the president can delegate to the FBI the authority to conduct national security investigations involving the use of surreptitious entries -- "black bag jobs."

Brownell, attorney general from 1953 to 1957, testified as a defense witness in the U.S. District Court trial of two former senior FBI officials who are charged with approving illegal secret entries at the homes of friends and relatives of fugitive members of the radical Weather Underground in 1972 and 1973.

The defendants, W. Mark Felt and Edward S. Miller, contend they had the authority of then acting FBI director L. Patrick Gray III to approve black bag jobs.

The defense has contended that President Nixon gave the late FBI director J. Edgar Hoover general approval to conduct the entries in connection with intelligence activities and that Gray assumed that authority when he was appointed director after Hoover's death in 1972.

The government argues that only the attorney general can be given that authority.

Brownell testified that he knew of no court ruling or law that would stop the president from passing on that authority to the bureau or any other government intelligence agency.

Under cross-examination by chief government prosecutor John W. Nields Jr. Brownell, who now practices law in New York, acknowledged that he has not kept up on legal developments in the area of constitutional protections against unreasonable searches and seizures.

During yesterday's court proceedings, the defense also introduced into evidence a September 1972 teletype from Gray to 28 FBI field offices, ordering them to conduct surveys and make recommendations for possible electronic surveillance and surreptitious entries in connection with the Palestinian terrorist organization Al Fatah or any possible support organizations in the United States.

Hoover had ordered black bag jobs related to national security cases stopped in 1966, and the defense is trying to show that the Gray teletype was intepreted throughout the bureau as a change in FBI policy.

Hunter Helgeson, formerly special agent in charge of a large Midwest field office, testified yesterday that in early 1973 his office carried out a surreptitious entry, directed at an American citizen, that was unrelated either to Al Fatah or the Weathermen.

The government charges that Felt and Miller targeted the Weathermen for black bag jobs in a desperate attempt to track down fugitive members. The defense presented evidence of other bag jobs not connected to the Weathermen in an attempt to show that such entries were carried out in other national security cases.