WASHINGTON--An out-of-control, radioactive Soviet spy satellite planed to fiery destruction in Earth's dense atmosphere over the mid-Indian Ocean yesterday, the Pentagon announced.

Air Force Cot. Robert O'Brien, a Pentagon spokesman, said U.S. observers on the island of Diego Garcia reported seeing a "40-second burn" in the sky at 5:15 EST, six minutes before the satellite's main hulk rammed fully into the dense atmosphere.

The North American Aerospace Command (NORAD) confirmed that the main body of the Soviet Cosmos 1402, estimated to weight about 8000 pounds, fell into the atmosphere at 5:21 p.m. EST.

At 6:10 p.m., the Federal Emergency Management Agency (FEMA) called off its worldwide alert and informed emergency teams standing by across the country to disband.

In a message to officials in all 50 states, FEMA said, "the public should be advised that protective action in connection with Cosmos 1402 is no longer necessary and thus the alert is over."

Pentagon officials said the satellite's "impact area" was about 980 nautical miles, 1127 statute miles southeast of the British-owned Island of Diego Carcia, where the United States maintains a naval base.

NORAD placed the re-entry point at about 25 degrees south Institute by 84 degrees east longitude.

"We do not know at this time whether any portion of the satellite reached the earth's surface intact," the Pentagon statement said. "U.S. nuclear fallout data collections assets have been instructed to watch for increased levels of radiation in the atmosphere, but it is impossible to say at this time what the result of this effort might be."

Air Force Lt. Col. Mark Foutch said these "assets" are U.S. ships and planes, equipped with devices which can defect radiation.

Defence officials said they planned so further statements for the remainder of the day.

A second and smaller portion of the satellite, sent into space last Aug. 30 to monitor movements of U.S. and other ships, remains in orbit and is expected to fall in mid-February.

The Pentagon has said this section "could contain radioactive nuclear fuel," which powered the satellite's radar.