AMSTERDAM (Reuters) - The international court set up to try the alleged killers of former Lebanese prime minister Rafik al-Hariri postponed on Thursday the provisional date for the start of their trial in absentia.

"A new tentative date will soon be set by Judge (Daniel) Fransen, to replace 25 March 2013 as a provisional date for the start of trial," the court said in a statement.

A pre-trial judge said the prosecution had not yet disclosed all its material to the defense, and therefore more time was needed.

The Special Tribunal for Lebanon was set up by the United Nations at the Lebanese government's request to try the alleged perpetrators of the 2005 bombing in which billionaire politician Hariri and 21 others were killed.

The suspects - Mustafa Amine Badreddine, a senior Hezbollah figure and brother-in-law of slain Hezbollah commander Imad Moughniyeh, Salim Jamil Ayyash, Hussein Hassan Oneissi and Assad Hassan Sabra - remain at large.

(Reporting by Thomas Escritt; Editing by Sara Webb and Tom Pfeiffer)