Investigators have told Scottish police that the bomb that destroyed Pan Am Flight 103 was put aboard in Frankfurt, West Germany, The Times of London reported Saturday.

The report said investigators are certain that luggage loaded on Flight 103 in Frankfurt and flown to London's Heathrow airport was transferred on arrival at Heathrow to the forward cargo hold of the doomed Boeing 747.It said scientists have established that the bomb exploded in that hold, causing the jumbo jet to disintegrate.

Flight 103 originated in Frankfurt, changed planes at Heathrow and continued to New York.

The jet crashed in the Scottish village of Lockerbie on Dec. 21 less than an hour after taking off from Heathrow, killing all 259 people aboard and 11 on the ground.

The account said the hunt for those responsible is now centered in Frankfurt "where a Palestinian terrorist cell is known to have been operating for more than 18 months."

It said the cell is known to be part of Ahmed Jibril's hardline Popular Front for the Liberation of Palestine-General Command and to have carried out two bombing attacks on U.S. military trains that serve Frankfurt.

The paper did not identify by name the source of its information.

It said Scottish police officers who flew to Frankfurt on Friday would be shown evidence of the terrorist unit's existence and are expected to be given access to a Palestinian man arrested by West German security forces two months ago.

It did not identify the man but said he is suspected of being a senior figure in Jibril's organization.

The paper noted that the Jibril group, in a statement in Damascus Friday, denied any connection with the crash. But it said the denial was regarded skeptically by terrorism experts, who believed the group was trying to avoid possible U.S. military retaliation.

An anonymous male caller claiming to represent a group called the Guardians of the Islamic Revolution telephoned American news agencies in London Friday to repeat a claim of responsibility and threaten further attacks.

The blue-and-white nose cone of Flight 103 was removed from the Scottish countryside Friday so investigators can examine the "symbol of this disaster" for clues to the bomb.

The search for wreckage expanded from Lockerbie and surrounding countryside into the waters of the Solway Firth, said Deputy Chief Constable Paul Newell of the regional police force.

He said the coast guard was acting on an eyewitness report that something fell into the inlet, about 20 miles from Lockerbie.

The airplane's nose cone and cockpit, with its name, "Clipper Maid of the Seas," still visible, had lain in a field beside a church for eight days, a silent reminder of the tragedy.

"The picture of this nose cone has been seen throughout the world," said police Chief Superintendent Angus Kennedy. "It has become a symbol of this disaster."

On Friday helicopters and trucks hauled the cut-up wreckage to the Royal Aerospace Establishment 300 miles south at Farnborough, southwest of London.

Investigators from the Department of Transport's Air Accidents Investigation Branch will examine it for clues about the bomb.

Police roped off an area near the wreckage where relatives of crash victims can place flowers.

The Times reported Friday that investigators believe the bomb's first trigger was a barometric device set to go off under a change of altitude. This would activate the second trigger, an electronic timer, to make the bomb explode at a later time, it said.

Terrorists developed the double detonator technique after some airports started putting cargo through pressure chambers that detonate pressure-activated bombs, The Times said.