A UN inquiry into the killing of former Lebanese PM Rafik Hariri has adjourned the questioning of five Syrian officials in Vienna, diplomats say.
Gen Rostum Ghazali is accused of helping co-ordinate Hariri's murder
Three Syrians will be interviewed on Wednesday after two others were questioned on Monday and allowed to fly back to Syria.
An interim report by the inquiry implicated Syrian and pro-Syrian Lebanese officials in Hariri's death.
Damascus has strongly denied involvement in the assassination.
Syria agreed to let the interrogations take place at the UN offices in the Austrian capital only after assurances that the officials would be able to return to Damascus afterwards.
The questioning has been veiled in secrecy, with the Syrians being brought in through a concealed entrance.
Arabic newspaper al-Hayat reported that Syria's former head of intelligence in Lebanon, Gen Rostum Ghazali, and an aide, Jama Jama, were questioned on Monday.
Head of the Syrian intelligence service's Palestinian affairs department, Lt Gen Zafir Youssef, Lt Gen Abd al-Karim Abbas, and retired Col Samih al-Qashaani will fly back to Damascus after being interviewed on Wednesday.
The UN Security Council has warned Syria it faces unspecified action unless it co-operates fully with the investigation.
Syrian President Bashar al-Assad has insisted there is no proof that his country was involved with the killing and wants the UN investigation to be fair and objective.