ABOARD THE USS RICHMOND K. TURNER, NOV. 26 -- This U.S. battle cruiser came within a hairbreadth of firing its missiles at three Iraqi warplanes in the northern Persian Gulf today after the planes approached in what officers believed was a threatening maneuver.

"They were flying in a ship-attack profile," said Capt. John D. Luke, commanding officer of the Turner. "They were flying low so that they would not be seen on radars. They were going fast, and they were coming toward us."

Officers aboard the cruiser, which has been on patrol in the northern gulf during the past few days, say they go on alert an average of two to three times per day because of Iraqi air activities.

On May 17, an Iraqi fighter-bomber hit the frigate USS Stark with two missiles, killing 37 American seamen. Iraq apologized for what it said was a mistaken attack.

Luke said there have been five or six previous incidents similar to today's in which the ship prepared to launch its long-range antiaircraft missiles.

"We didn't have much more to go until we fired," he told members of a Pentagon news pool who were aboard the ship. "It was just a gut feeling" not to fire, he added.

The incident occurred as the Turner's crew was sitting down for a Thanksgiving meal. Luke, who was greeting sailors at the mess line, rushed back to his command center to deal with the crisis.

The ship went to its highest state of alert, after its radar picked up the three Iraqi F1 Mirages moving south along the Saudi Arabian coast. The planes ignored several radio warnings before the alert was signaled through the ship, officers said.

Luke would not say how close to the American ships the Iraqi planes had come but said, "if you had been on deck you might have been able to see them."

In the southern gulf today, an Iranian frigate shelled a tanker of unknown registry, setting it ablaze as its captain yelled into his radio, "Any Russian warships, I need immediate help!"

{The attack occurred so close to the coast of Dubai, United Arab Emirates, that the gunfire delayed a flight at the airport there, Reuter reported.}

The tanker captain identified his ship as the 86,940-ton Dacia, a Romanian-registered vessel, but the state-run Romanian oil company said its ship was in the Black Sea.

The Iranian frigate opened fire on the tanker after the U.S. helicopter carrier Okinawa had departed the area, having attempted to warn the tanker away from the Iranian vessel.

Lloyds Shipping Intelligence Unit in London confirmed that the attacked tanker was named Dacia but said it appeared to be a Kuwaiti-owned vessel whose name had been changed. The mystery raised the possibility that Kuwait is disguising some of its ships to avoid being attacked by Iran.

Meanwhile, Tehran's official news agency reported that Iranian officials have detained an alleged Saudi Arabian spy, who was not identified, for suspected involvement in riots in Mecca, Saudi Arabia, last July in which 275 Iranian pilgrims were killed.

The announcement came as a congress of Moslem scholars from 36 nations met in Tehran to discuss an Iranian proposal that would strip Saudi Arabia of its right to administer Moslem holy shrines there.