BOSTON, JULY 8 -- -- Political extremist Lyndon H. LaRouche Jr. claimed today that his indictment here last week was partly the result of covert operations conducted by Lt. Col. Oliver L. North and the National Security Council.

LaRouche was indicted for allegedly trying to block an investigation into whether he, 13 of his aides and five of his organizations conducted a $1 million credit-card fraud scheme to finance his 1984 presidential campaign.

He pleaded not guilty Tuesday to the charge that he ordered his followers to burn and shred campaign finance documents, and to leave the Boston area so they could not be questioned by investigators.

LaRouche, 64, faces up to five years in jail and a $250,000 fine if convicted.

LaRouche charged today, as he has before, that North and the NSC were "involved in operations against me," and that the NSC worked with the Justice Department to secure the indictment, which LaRouche described as phony. He said friends of his were approached by North after North was fired from the NSC in November.

LaRouche said North wanted advice on what he should do about the Iran-contra affair. He said he told his friends to tell North nothing.

LaRouche has previously said that North ran a secret government squad that "targeted" LaRouche and his associates because of a competition for funds.

LaRouche associates have harshly denounced the Nicaraguan counterrevolutionaries, or contras, while North was involved in efforts to aid them. LaRouche denied today that he ordered workers to destroy documents or to leave Boston. But he said he advised fund-raising workers to give up their posts while the investigation was under way.