DUBAI, UNITED ARAB EMIRATES, DEC. 15 -- An Iranian frigate fired on a Greek tanker that failed to respond to a radio warning in the southern Persian Gulf today, setting off a massive explosion that forced the crew to abandon ship, shipping sources said.

They said the frigate warned the captain of the 102,088-ton Ariadne, now burning and listing off Jebel Ali, near Dubai, three times that it would open fire unless he replied.

"The frigate said, 'Respond or I will open fire,' " one source said. "He said it three times. There was no response. Then he opened up with his five-inch gun."

A huge explosion ripped open the deck of the tanker, on its way to load oil at Ras Tannurah in Saudi Arabia, but no one was hurt.

The attack followed unconfirmed reports from Norwegian shipping officials that 21 members of a Norwegian-operated tanker chartered by Iran, the Susangird, were killed in Iraqi Air Force missile attacks last week. {The Associated Press quoted the Susangird's Oslo-based operators as saying that two of the 218,467-ton tanker's crew of 27 were killed, five were hospitalized in Tehran and the rest are missing and presumed dead.}

Tehran follows a policy of retaliating against merchant shipping in the Gulf whenever Iraq attacks ships serving Iran.

The shipping sources said the U.S. destroyer Chandler was close to the Ariadne -- it was spotted half a mile away after the explosion -- but took no action because its rules of engagement prohibit defense of a non-American ship.

The shipping sources said the frigate opened fire after shadowing the Ariadne for seven hours. They said it began following the tanker after speedboats of Iran's Revolutionary Guard sprayed it with machine-gun fire in a raid just after dawn, starting a small fire that the crew put out unassisted. "They have been hunting her all day," one source said. of 27 were killed, five were hospitalized in Tehran and the rest were missing and presumed dead.}

Tehran follows a policy of retaliating against merchant shipping in the Gulf whenever Iraq attacks ships serving Iran.

Reuter AP-NY-12-15-87 1228EST