If true, the concession would limit the scope of the trial and make it difficult to implicate Libyan leadership in the 1988 PanAm blast.
The United States and Britain agreed that no other Libyans would be tried or arrested "even if there were existing or new charges" against them, said Prince Bandar Bin Sultan, Saudi Arabia's ambassador to the United States.
Bandar, who helped South African President Nelson Mandela negotiate Libya's surrender of the two suspects, also said there was a "written pledge from the United Nations as a guarantor that the two (suspects) will be tried only for the Lockerbie case." He did not elaborate.
Bandar's comments were published in the London-based Asharq al-Awsat newspaper on Friday.
Asked if the United States could summon Libyan leader Moammar Gadhafi or government officials as witnesses, Bandar said, "These are wrong assumptions, and the charge sheet is limited to two people only."
Abdel Basset Ali al-Megrahi and Lamen Khalifa Fhimah were handed over Monday for trial by a special Scottish court in the Netherlands. They are accused of blowing up PanAm Flight 103 over Lockerbie, Scotland in December 1988, killing 270 people. The two were arraigned on Tuesday.
Al-Megrahi, 46, and Fhimah, 42, are charged with murder, conspiracy to commit murder and violations of international aviation security laws.
Under Scottish law, their trial should begin within three months of arraignment. However, lawyers for the two men are expected to request an extension to give them more time to prepare their defense, which could delay the trial's start by six months to a year.
Once the trial gets under way, it is expected to take a year or longer. If convicted, the suspects -- both of who insist they are innocent -- will serve their sentences in Glasgow's Barlinnie jail, Scotland's highest-security prison.
They face up to life imprisonment; Scotland has no death penalty.
After their surrender Monday, the United Nations suspended sanctions that were imposed on Libya 1992 for failing to surrender the suspects. The U.N. Security Council said it would consider lifting the sanctions altogether if Libya publicly renounces terrorism and complies with other U.N. demands.
On Friday, Switzerland followed the United Nation's lead and suspended sanctions against Libya. Switzerland, because of its historic neutrality, is not a member of the United Nations, but it had slapped its own embargo on Libya in 1994.
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