The search for victims of the Pan Am Flight 103 disaster and clues as to its cause has spread over a broad area, and police Monday probed reports that looters also were scouring the hilly, wooded region.

The violence of the disaster in southwest Scotland was such that five days after Britain's worst-ever aviation wreck, it has not yet been possible to identify even one of the 239 bodies recovered.Searchers still have to find an estimated 30 more bodies.

"We still have areas which are almost impregnable," deputy Chief Constable Paul Newall said Sunday. "Some of the forestation is very, very hard to get into - very difficult to see into from the air, even from the best helicopters."

And, he added, "lots of our people are getting fairly tired." Some of the sniffer dogs which help search for bodies were so weary they were given Christmas Day off, he said.

Police said Monday that they had arrested a local 28-year-old man on suspicion of looting. The announcement followed reports in The Sun, Britain's largest-circulation newspaper, that looters were scouring wreckage from the plane under cover of night in search of rings, jewlery and cash.

Police said the suspect might be taken before the sheriff's court in Dumfries when it reopens on Wednesday.

Police spokesman Angus Kennedy said steady rain Monday hampered a helicopter survey of the search corridor, which now extends about 15 miles east of Lockerbie, where most of the Boeing 747 rained to the ground in large pieces.

No more bodies were found on Sunday. Pan Am said 258 were aboard the night flight to New York, and 11 townspeople are listed as missing.

A bomb or structural failure are considered the most likely causes of the disaster.

A police statement Sunday said Mick Charles, who heads the British Department of Transport team probing the crash, "is now engaged in intensive investigations of the examination of fragments over a large area . . . and further comment at this stage would be premature."

But one expert on air disasters was quoted Monday as saying he thought structural failure to the rear of the cockpit was the cause.

William Tench, Britain's former chief inspector of air accidents and now a consultant on aircraft accidents to the Defense Ministry and the European Economic Community, told The Times of London there was no evidence so far of a bomb.

Tench said the jet's left wing, which has not been found, could have fallen into the sea - ripped off as the nose tore away. The wind could then have blown the wing into the sea, which is just 10 miles south of Lockerbie.

"If the wing had broken off at the root, the disruption of the electrical system would have been substantial, possibly precluding the sending of a mayday (distress) call," Tench was quoted as saying.

"If the wing is missing, this raises the question of whether there was a structural failure resulting from over-stressing in extreme weather conditions, which were in the area at the time," The Times quoted Tench as saying.

The search area was initially concentrated between the west side of Lockerbie, where the exploding wreckage destroyed four houses and damaged 20 more, and Tundergart Mains, three miles to the east, where the cockpit fell near a country church.

Newall said Sunday that the search now goes as far as 15 miles east of Lockerbie.

The dismal weather on Sunday did not prevent relatives of victims from visiting some of the wreckage, including the cockpit.

"I think it's been important for them to see something that is still to some extent recognizable as part of an aircraft," said Leslie Jardine, a spokesman for social workers who have been assisting the bereaved visitors.

He said 61 relatives, most of them Americans, were in town Sunday.

Kennedy said bodies would be released for burial as they are identified. However, the chief pathologist, Dr. Anthony Busuttil, has found that few bodies can be identified on sight and examiners must rely on such things as X-rays and dental charts, according to a statement issued by police.