Fear of disclosing intelligence sources and methods has quashed a House investigation into charges that Rep. Edward J. Derwinski (R-Ill.) warned the South Korean government last year that one of its intelligence agents planned to defect.

Rep. Lee Hamilton (D-Ind.), who headed the inquiry for the House Committee on Standards of Official Conduct, said yesterday that "publication of the evidence (held by the intelligence community) would jeopardize intelligence sources and methods."

A federal grand jury also investigated the case last year without returning an indictment. The Washington Post reported then that a U.S. intelligence intercept of a phone call to the Korean embassy apparently implicated Derwinski.

Attorney General Griffin B. Bell then referred the case to the House for possible action.

The official committee announcement yesterday by Chairman John J. Flynt Jr. (D-Ga.) said only that "insufficient evidence" prevented the ethics unit from taking action. His statement did not mention Derwinki.

Derwinski has denied that he told the Koreans last fall about the imminent defection of Soh Ho Young after the Korean CIA officer contacted a House International Relations subcommittee on which the congressman served.

Derwinski said yesterday that he has never been questioned by House investigators about the allegations. Rep. James H. Quillen (R-Tenn.), another eithics committee member, told Associated Press yesterday that Derwinski was "completely cleared" by a Hamilton investigation.

But another source close to the investigation said the unusable intelligence information definitely pointed to Derswinski as the leak.

FBI agents rescued Sohn last fall about half an hour before alerted KCIA officials arrived at Sohn's home to stop the planned defection. Sohn later testified about a 1976 KCIA plan to buy influence in the United States.

U.S. intelligence agencies commonly resist attempts to use information gathered by their supersecret intercepts of embassy cable traffic, or by double agents, as a basis for prosecuting alleged criminal conduct. They argue their sensitive techniques must be safeguard.

Investigators complain, however, that foreign governments already know their messages are likely to be intercepted even by allies, and that the fear of disclosing "sources and methods" prevents the punishment of guilty individuals.