Traces of materials used to make Semtex were found on metal recovered from the baggage container of doomed PanAm Flight 103, a pioneer in the field of explosives analysis told the Lockerbie trial yesterday.

Dr John Douse was giving evidence at the specially-convened Scottish court at Camp Zeist, in the Netherlands, where two Libyans stand accused of bombing the New York-bound Boeing 747.

The 47-year-old, who worked in the Metropolitan Police's forensic laboratory, was giving evidence on the fourteenth day of the trial.

He told the court in 1988 he went to work at the Royal Armaments Research and Development Establishment, at Fort Halstead, in Kent, where he was asked to examine two sections of the plane. Questioned by prosecuting counsel Alistair Campbell QC, he told how swabs were taken from two pieces of wreckage with a special solution in order to remove any potential traces of explosives.

Further procedures were followed before the samples underwent a process known as Capillary Gas Chromotography, a technique first ''successfully applied'' by the doctor in that field. Dr Douse told the court how the possible presence of PETN and RDX were detected during the test from fragments of the baggage container. When asked whether he was aware that both could be used in the manufacture of Semtex, the doctor replied: ''Yes.''

Mr Robert Griswold, 53, of Colorado, USA, earlier identified shattered fragments from a suitcase gathered in the wake of the disaster as being of a Samsonite brand. He told the hearing how he had worked at the company's Denver plant as a manufacturing analyst for 33 years before retiring in January. The court heard how a bolt mechanism recovered from the debris revealed the case as being from the Silhouette 4000 range while a small hole showed it was 26in in size.

Abdelbaset Ali Mohmed Al Megrahi, 48, and Al Amin Khalifa Fhimah, 44, deny three alternative charges of conspiracy to murder, murder and a breach of the 1982 Aviation Security Act.

They have lodged special defences of incrimination blaming, among others, members of the Popular Front for the Liberation of Palestine - General Command (PFLPGC), for the atrocity.

The defendants are alleged to have caused a suitcase containing an umbrella, clothing and an improvised explosive device concealed within a radio cassette recorder to be placed on board the doomed plane.

All 259 passengers aboard Pan Am Flight 103 perished when the aircraft exploded on the evening of December 21, 1988, and 11 Lockerbie residents were killed after the plane plunged to the ground.