Speaking at a conference on the trial at the Arab League headquarters in Cairo, Austrian philosophy Professor Hans Koschler said there appeared to be pressure from the USA and UK.

Prof Koschler was one of five people appointed to observe the trial held at the Scottish Court in Camp Zeist in the Netherlands.

Abdelbaset Ali Mohmed Al Megrahi was sentenced to life in prison after being found guilty of the killing of 270 people in the 1988 bomb attack on Pan Am Flight 103.

Al Megrahi's lawyers have launched an appeal

His co-accused Al Amin Khalifa Fhimah was acquitted and has since returned to a hero's welcome in Tripoli.

Prof Koschler, who said his views were his own and not those of the United Nations, said: "The present judgment is logically inconsistent.

"You cannot come out with a verdict of guilty for one and innocent for the other when they were both being tried with the same evidence.

"In my opinion, there seemed to be considerable political influence on the judges and the verdict.

"My guess is that it came from the United States and the United Kingdom. This was my impression."

The Innsbruck University professor said he had submitted his report on the trial to UN General Secretary Kofi Annan, who had forwarded it to the Scottish authorities.

Sanctions question

The conference was expected to discuss Libyan demands for sanctions to be abolished.

Both US President George W Bush and UK Prime Minister Tony Blair have said that sanctions will not be lifted until Libya accepts responsibility for the bombing and pays compensation.

Al Megrahi's legal team are appealing against his conviction.