Congressional leaders have asked the Justice Department to give them access to secret U.S. intelligence reports considered vital to an investigation of how much the executive branch knew about the South Korean lobbying campaign on Capitol Hill.

Attorney General Griffin B. Bell has refused so far on the grounds that Rep. Edward Derwinski (R-III.), the ranking minority member of the House international organizations subcommittee, is suspected of leaking information to the Korean government, according to sources familiar with the controversy.

A federal grand jury investigated allegations last fall that Derwinski warned the South Korean government about the imminent defection of one of its intelligence agents. The jury did not return an indictment, but delivered a sealed report on its findings to a federal judge, who refused to release it.

Derwinski has denied the charges.

Last week, Bell forwarded a separate summary of the prosecutors' findings to House Speaker Thomas P. O'Neill Jr. for possible disciplinary action against Derwinski, knowledgeable officials said yesterday.

O'Neill then sent the packet of material to the House Committee on Stardards of Official Conduct which is responsible for policing the ethical conduct fo members, sources said. That Committee is in the midst of a separate investigation of the alleged Korean influence buying scheme.

O'Neill was drawn into the dispute between the executive branch and the House international organizations subcommittee headed by Rep. Donald Fraser (D-Minn), earlier this week.

Fraser's subcommittee is planning to hold hearing late this month on the question of executive branch awareness of the Korean lobbying [TEXT OMITTED FROM SOURCES]

After Fraser had an unsuccessful meeting with Bell last Monday, he appealed to O'Neill fro support. The speaker called Bell on Wednesday and asked for a meeeting with top congressional leaders, an O'Neill aide siad yesterday.

Fraser, O'Neill, Rep. John Rhodes (R-Ariz.) and Rep. Clement Zablocki (D-Wis.), chairman of the House International Relations Committee, are scheduled to meet with Bell this Tuesday afternoon in an attempt to settle the impasse, the O'Neill aide said.

The conflict takes on added significance because the Fraser subcommittee is investigating the executive branch in this instance. Some congressional sources have raised questions about the validity of Bell's objections, especially since Derwinski was not indicted in connection with the suspected leak of sensitive information.

It is apparent from what has been made public about the investigations so far that American intelligence agencies picked up explicit warnings in the early 1970s that the Korean government planned to give members of Congress cash and gifts to ensure continued U.S. aid.

During its study of Korean-American relations, the Fraser suncommittee has been attempting to determine what executive branch officials learned about the illegal campaign and why they did nottting to sop it.

That phase of the subcommittee investigation was hampered last fall when suspicions about the alleged Derwinski leak caused the intelligence agencies to hestate about providing confidential documents about the Korean lobbying scheme.

But the simmering dispute apparently did not reach a critical stage until recently, when Fraser went to Bell with his request for access to a key group of intelligence documents considered necessary to prepare fro the upcoming hearings.

One source said yesterday that it was his understanding that the Justice Department was more concerned about the security of the documents in question than the intelligence agencies.