Leon Jaworksi, special counsel for the House investigation of South Korean influence-buying, wants interrogation authority broader than ever granted before except in the impeachment inquiry of former President Nixon.

Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) said yesterday he supported the request, which would permit attorneys on the staff of the House Committee on Standards of Official Conduct to take sworn testimony from witnesses without a committee member being present.

The rationale is that the change would speed the committee's work during floor votes and recesses when members are absent.

Reps. John Flynt Jr. (D-Ga.) and Floyd Spence (R-S.C.), the chairman and ranking minority member of the committee, introduced a resolution to make the exception to the general House rule. It is expected to be voted on later this week.

Peter Robinson, an assistant House parliamentarian, said yesterday that the only precedent for such staff automony was the authority granted the House Judiciary Committee during its 1974 impeachment investigation.

Staff members on that investigation recalled yesterday that the authority was used only once and then stopped because of complaints by members.

The House Rules Committee delected the same proposal when it came up in February in the original resolution authorizing the Korean inquiry.

Rules Committee members indicated then that they didn't want the staff to have such power for fear the investigating committee's members would in uninvolved.

Rep. Bruce J. Caputo (R-N.Y.), the junior member of the Standards of Official Conduct Committee, said yesterday he will oppose the change, on grounds that it would be an "undue delegation to the staff" and would mean treating witnesses unequally.