President Reagan acknowledged to Iran-Contra prosecutors that in April 1985 he persuaded a Central American leader to release an arms shipment to the Nicaraguan Contras during the congressional ban on such aid, court documents showed Monday.

Sources familiar with Reagan's request said the country is believed to be neighboring Honduras.Reagan's request was described in a document filed in federal court by independent prosecutor Lawrence Walsh, who is required to divulge material that would exonerate former White House aide Oliver North, the first to stand trial in the complex conspiracy case.

Walsh listed Reagan's request in a July 28 letter to North attorney Barry Simon.

North, the central figure in the covert operation, contends that his actions involving the secret sale of arms to Iran and the diversion of the profits to the Contras were known to and approved by superiors.

Reagan's request, first disclosed during last year's congressional hearings into the foreign policy affair, would appear to buttress North's arguments.

In May 1987 testimony, former national security adviser Robert McFarlane said he asked Reagan to ask the head of state of a Central American country in April 1985 to release a confiscated arms shipment intended for the Contra rebels. McFarlane said Reagan was successful in getting the arms released.

Reagan, responding in writing to questions from Walsh, repeated the administration's contention that the 1984-1986 congressional ban on aid to the Contras did not apply to the National Security Council staff, which included North.