Investigators combed through the wreckage near Stansted Airport, 38 miles north of London, examining debris and looking for remains of the 747's four crew members. British transport officials, meanwhile, ordered special pre-flight checks of Korean Air planes operating in Britain.
In Seoul, the South Korean government extended for another six months -- until May 2001 -- a ban on Korean Air's adding new international routes or flights.
Korean Air, the world's 13th-largest airline, has suffered a series of accidents at home and abroad in recent years.
On Wednesday, there were no distress calls from the pilot to air traffic controllers in the moments before the crash, said Charles Clark, assistant chief constable of Essex County police.
"Whatever happened, the pilot didn't get a chance to call back on it," he said, adding that it was unclear whether the explosion occurred in the air or when the plane hit the ground.
There were no casualties on the ground, where local residents expressed relief they were spared as they watched the aircraft hurtle over homes in flames near Great Hallingbury, three miles southeast of the airport.
Clark said it would take several days to sort through the wreckage, which was stretched over about one square mile from the end of the runway, through fields and into a forest. Debris landed about 100 yards from a farmhouse.
Investigators have located the cockpit voice recorder.
The 19-year-old Boeing 747-200F plane -- which a Boeing spokesman said had made at least 15,000 flights -- was bound for Malpensa Airport in Milan, Italy with 64 tons of cargo.
The airline said the cargo included electronic goods.
Tony Lilliott, Assistant Chief Fire Officer for Essex county, said 4.4 pounds of explosives -- in the form of detonating cord, or fuse -- were on board, but that it simply would have burned away. He said the fireball probably came from burning fuel.
In Seoul, Korean Air spokeswoman Cho Mo-ran identified the four crewmen as pilot Park Duk-kyu, 57; co-pilot Yoon Ki-sik, 33; engineer Park Hun-kyu, 38, and maintenance mechanic Kim Il-suk, 45.
"We're sorry that this happened while we're putting lots of efforts and money into strengthening safety measures," Korean Air's chief spokesman Han Sang-bum said at a news conference.
Last month, the South Korean government banned Korean Air from adding new international routes and flights for one year after U.S. investigators held its pilots mostly responsible for a 1997 jet crash in Guam that killed 228 people.
If the airline is found responsible for the London crash, it could face stiffer sanctions including fines or the loss of existing routes, said Kim Chang-sup, a director-general in South orea's Ministry of Construction and Transportation.
In Britain, transport officials said Korean Air had already been subject to special pre-flight safety checks before the crash but that they had yielded no cause for concern.
"We were aware of the Korean safety record and had asked the Civil Aviation Authority to intensify (pre-takeoff inspections) of their aircraft. Further assurances had also been sought from the Korean authorities, which had been given," said a Department of Transport spokesman, speaking on condition of anonymity.
"No evidence was found to lead us to ground these aircraft. Further ramp checks will now be carried out" on other Korean Air planes, he said.
In April, a KAL cargo plane crashed shortly after takeoff from Shanghai's airport, killing all three crewmen and five people on the ground.
In 1998, KAL passenger jets were involved in three incidents of jets skidding off runways or bell-landing, injuring a total of 128 people.
©1999 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed