Madrid - Prosecutors at Spain's National Court on Thursday asked judge Ismael Moreno to widen his investigation into alleged US flights transporting terrorism suspects via Spain to the prison camp in Guantanamo, Cuba.

The prosecutors urged Moreno to question the author of a top secret Foreign Ministry document which was published by the daily El Pais.

The 2002 document indicates that former prime minister Jose Maria Aznar's conservative government gave the United States permission to secretly transport Taliban and al-Qaeda prisoners from Afghanistan via Spain to Guantanamo.

A Foreign Ministry commission investigating the allegations has been unable to locate the original copy of the document, which was written by senior official Miguel Aguirre de Carcer.

The prosecutors also requested other additional information on the alleged flights, such as the identification of people who might have witnessed their stopovers at military bases in Spain.

Jaime Garcia Legaz, a representative of the conservative FAES foundation headed by Aznar, denied Thursday the existence of a "secret pact" between outgoing US President George W Bush and Aznar, who was Bush's staunch ally, on flights organized by the US Central Intelligence Agency (CIA).

Spain's conservative opposition claims that most US flights which could have transported prisoners took place under current Socialist Prime Minister Jose Luis Rodriguez Zapatero, who took office in 2004.

Zapatero has denied knowledge of such flights.

The government earlier handed the National Court documents on 11 flights making stopovers in Spain on their way to or from Guantanamo - and 13 others which used Spanish airspace - between 2002 and 2005.

The new allegations concerning the flights have raised the possibility that members of the Aznar government could be sued for cooperating with the US in illegally imprisoning suspects at Guantanamo.

Josep Pique, who was foreign minister in 2002, was booed and called a "torturer" while giving a lecture at a Madrid university on Wednesday.

A Council of Europe 2006 report named Spain as one of several countries having allowed secret CIA flights carrying terrorist suspects. (dpa)