Oliver North's lawyers say the government is refusing to admit that President Reagan and other top administration officials hid a policy of offering inducements to third countries for their support of the Contras.

In a court filing Wednesday that was made public Friday, North attorneys said independent counsel Lawrence Walsh "fails - for the fourth time - to acknowledge" that Reagan and other officials established a policy that "the quid pro quo and other third-country arrangements would not be disclosed."The filing by lawyers Brendan Sullivan and Barry Simon reflects the courtroom fight that was continuing Friday behind closed doors as North's lawyers push for greater disclosures of arrangements which they have called the heart of the case.

U.S. District Judge Gerhard A. Gesell has said he will accept an admission of fact from the government on the arrangements rather than allowing North's lawyers to present the matter in detail in open court. The issue involves substantial amounts of classified material.

In its proposed admission, the government on Tuesday sggested that "North alone was responsible for devising a means of concealing a quid pro quo arrangement from Congress," North's lawyers said. They said the independent counsel's proposed submission on that point "is grossly misleading and patently inadequate."

"If the defense must be satisfied with a cold admission on the quid pro quo issue - and must give up its right to present the many documents and the extensive live testimony that would bring the issue to life for the jury - then it must also have an admission on the non-disclosure policy," said North's lawyers.

They insisted that information be included "setting forth particular instances in which Executive Branch officials withheld information concerning quid pro quo and other third-country arrangements."

North's attorneys also said they want to supplement the government's admission with specifics of inducements the United States offered third countries to persuade them to support the Contras.

On Tuesday, Gesell ordered Thornburgh to stay out of the Iran-Contra case, saying it was up to Walsh to prevent the introduction of classified information. Walsh's office, in meetings with the Justice Department, then worked out the notification plan.