A delegation from the International Criminal Court has visited four colleagues who are detained in Libya since last week.
The group, including an Australian defence lawyer, Melinda Taylor, are accused of trying to smuggle documents to Colonel Gaddafi's son, Sayef, the BBC reports.
Gaddafi is being held by militiamen in the mountain town of Zintan, some 150km south of Tripoli. He was captured last November.
Libya's interim government has so far refused to hand him over for trial in the Netherlands. It has insisted he should be tried by a Libyan court.
The ICC delegation travelled to Libya on 6 June and were taken prison last Thursday. They are reportedly being held under house arrerst and not in prison.
The ICC is demanding their release. ICC president Sang-Hyun Song said they have immunity when travelling on an official mission.