The trial of Colonel Gaddafi's son will be delayed by five months to include any relevant testimony obtained via the interrogation of Libya's former spy chief, who was arrested last week.

Government officials said in August that Saif al Islam's trial on charges of war crimes – the most high-profile prosecution of a figure from his late father's entourage to date – was due to begin in September.

However, the arrest on Wednesday of Abdullah al Senussi, the former spy chief known as "Gaddafi's black box", has pushed the start date back, postponing a trial that a lawyer from the International Criminal Court (ICC) has already said is unlikely to be fair.

Prosecutors in Scotland working on a fresh inquiry into the Lockerbie bombing have said they will pursue all available lines of inquiry with Libyan authorities, following the extradition of Mr al Senussi.

He is thought to be key to any inquiry into the 1988 atrocity in which 270 people died, and the murder of police woman Yvonne Fletcher in London four years earlier, which is being investigated by Scotland Yard.

Lord Advocate Frank Mulholland travelled to Libya in April to meet Prime Minister Abdurrahim el Keib and pave the way for a new Lockerbie inquiry, announced last autumn.

A statement from the Crown Office said: "We note the position in relation to the extradition of Mr al Senussi to Libya and we will continue to liaise with our colleagues in the Foreign and Commonwealth Office, as well as the Libyan authorities, to pursue all available lines of inquiry."