Jose I. Blandon, a former top aide to Panamanian strongman Gen. Manuel Antonio Noriega, met under heavy guard yesterday at the U.S. Courthouse here with prosecutors investigating the Iran-contra affair.

Blandon has said Noriega agreed to train Nicaraguan rebels at the request of Lt. Col. Oliver L. North, a former National Security Council official who is a target of independent counsel Lawrence E. Walsh's investigation.

Blandon, a former Panamanian intelligence official, was escorted by heavily armed U.S. marshals as he arrived at the courthouse.

Blandon has assisted federal prosecutors in Florida, who earlier this month obtained indictments charging Noriega with taking at least $4.6 million in bribes to protect a major Colombian drug ring.

Blandon recently testified to the Senate Foreign Relations Committee that Noriega agreed to train Nicaraguan anti-Sandinista rebels after receiving a request from North in 1985.

North sought the training on Panamanian soil because Congress had banned direct U.S. military aid to the rebels, Blandon said.

Blandon, fired last month as Panama's consul general in New York, told the committee that North met Noriega on a yacht in June 1985 near the Panamanian city of Balboa and again, four months later in Noriega's office.

According to Blandon, Noriega offered to send Panamanian soldiers to Nicaragua on "terrorist sabotage" missions, but North said he had no authority to accept such an offer.