The government has ended its investigation of a report that Sen. Birch Bayh (D-Ind.) took an illegal contribution from a South Korean businessman, and plans no action against him, Deputy Attorney General Benjamin R. Civiletti said yesterday.

Asked if that meant that Bayh had been cleared of any wrongdoing, Civiletti repeated that the case had been "closed without any action." He added that it was "not a difficult decision" to make.

In October, the Senate Ethics Committee asked the Justice Department to look into charges that Bayh or an aide accepted a $1,000 contribution from an associate of South Korean businessman Tongsun Park at the Capitol, Federal law prohibits accepting campaign contributions on government porperty.

Bayh denied any wrongdoing. He said the money was properly received through the amils.

Edward L. Merrigan, a lobbyist associated with Park, had testified that the contribution was made in Bayh's office.

The Ethics Committee requested the Justice Department to look into the possibility of perjury in the case.

Civiletti also told reporters that the so-called Koreagate investigation was winding down.

He said some things remain to be done, including the possibility of a perjury prosecution involving one or more public officials. He declined to be more specific.

On other matters, Civiletti said he expects to make a recommendation to the White House "within 30 days, if not sooner," on whether President Carter should commute the sentence of convicted bank robber Patricia Hearst.

Hearst, 24, has served nearly 22 months of a seven-year sentence following her switch from kidnap victim to bank robber, but is not eligible for parole until July.

She filed a petition asking executive clemency in September, and Attorney General Griffin B. Bell -- who has the option of reviewing the case before it goes to the White House -- has publicly expressed sympathy for her plight.

Asked about the status of her petition, Civilietti said: "It's in my lap right now. I'll have it out of my lap. I'm hopeful, within 30 days, if not sooner."

Civiletti sais the Justice Department has some good leads into the disappearance of former Teamsters union President James R. Hoffa.

"We have a lot of information which we believe to be accurate, and some sound ideas," Civiletti told reporters.

But he said he did not know who may have killed Hoffa, adding: "I can't answer for the FBI. They have some good ideas about what happened."

Civletti said the investigation of Hoffa's disappearance "has produced information we've never had before on high-level crime figures," He said the investigation was still "very much open," and "I think it has high priority."