The Defense Department disclosed yesterday that it withheld five media reports written Monday by journalists aboard Navy ships in the Persian Gulf because the dispatches contained "sensitive" details of the Kuwaiti tanker escort operation.

The writers are part of a pool system established by the Pentagon after the news media objected to being excluded from covering the U.S. invasion of Grenada in 1983. This is the first time the pool has accompanied a military mission, although there have been practice exercises in the past.

On-the-record interviews with the captain of one of the escort ships and details of the operation supplied by Navy personnel were included in the delayed reports. The details included the 16-knot speed that the ships would travel, the number of ships the Navy would use and that the two tankers being escorted would travel one mile apart.

Knight-Ridder Newspapers, which has a reporter in the group of 10 journalists aboard the ships, complained that the Pentagon had unnecessarily delayed release of the reports.

The Pentagon released the four reports yesterday morning and later handed out another nine dispatches with little or no delay. Because the reporters are at sea and cannot communicate independently with their editors, they rely on the military to transmit their dispatches.

Defense Department spokesman Robert B. Sims said yesterday he did not anticipate the Pentagon would withhold any more dispatches because the convoy of three Navy ships and two reflagged Kuwaiti tankers had passed the most dangerous part of its voyage and could no longer be compromised by news reports.

Sims said he had no regrets about withholding the articles, asserting that they contained information that added to the risk to American personnel on the Navy ships and might have jeopardized the success of the operation.

"I have to make a judgment, and my priority is going to be on whether or not I think {the reports} will add to the risk or endanger American lives," he said. "And if it's a question of adding to the risk . . . versus an hour or two of releasing a report, I'll wait an hour or two."

Clark Hoyt, Washington bureau chief for Knight-Ridder news service, charged in a letter to Sims yesterday that the reports were subjected to "completely unsatisfactory delays" and said that the Pentagon had no right to "censor" information supplied on the record by experienced naval officers.

Charging that the Pentagon's actions amounted to "censorship by delay," Hoyt said that in a meeting Pentagon officials held with representatives of the news organizations sending reporters on the ships, no restrictions on use of specific mission information were discussed.

Under guidelines for press coverage of military operations, the Defense Department can withhold dispatches it believes include precise details about about military missions.

The reports came from a group of 10 Washington-based reporters aboard the destroyer USS Kidd and the cruiser USS Fox. The two ships are participating in the first escort convoy, which passed through the Strait of Hormuz along the Iranian coastline and entered the Persian Gulf without incident yesterday.

Press guidelines adopted last year by the Pentagon stipulate that news organizations with reporters regularly covering the Defense Department are allowed to participate in a reporting pool that can be activated in the event of a military operation. Journalists called by the Pentagon on Saturday to join the pool include reporters from The Associated Press, Knight-Ridder Newspapers, The Washington Times, Time magazine and ABC radio, a Cable News Network television crew and photographers for United Press International and Time.

No videotape or film has been "aken off the ships because no helicopters have been available to transport it, according to Col. Marv Braman, director for defense information at the Pentagon. He said transportation should be available today.

Audio material was not yet available because the Navy ships could not establish a radio connection clear enough for broadcasting, Pentagon officials said.