Aids is a major killer throughout Africa
The French doctor who first isolated the
HIV virus has said a hospital Aids epidemic in Libya
was probably caused by poor hygiene, and not by the seven medical workers who are on trial on charges of deliberately spreading the disease.
A Bulgarian doctor and five nurses, as well as a Palestinian doctor, are accused of infecting about 400 children with HIV, the virus which can lead to Aids, at a hospital in Benghazi.
The case was dismissed last year for lack of evidence, but the prosecution refiled charges.
A BBC correspondent says diplomats have suggested the case could be an attempt to divert attention from the conditions in Libya's state-run hospitals.
There are also suggestions that Libya might be trying to pressure Bulgaria into forgiving its debts, estimated at $300m.
On the first day of the hearing, Professor Luc Montagnier presented a report he had made on the case, showing the infection had already begun before those accused started working at the hospital, and continued to spread after they were arrested.
"This can happen not only in this hospital, but in many others, particularly paediatric hospitals, because children are more vulnerable to infection, even by very small quantities of blood," he told Bulgarian radio after testifying in court.
Professor Montagnier and Italian Aids scholar Vittorio Collizzi have studied the case, following a Bulgarian request for an independent international assessment.
The seven accused were working at the al-Fateh children's hospital in Benghazi in 1998, when several children died without any immediately apparent cause.
The case became a major international incident between Libya and Bulgaria, which called on the help of a number of Arab, African and Western countries to intercede on its behalf to ensure a fair trial, says the BBC's Sebastian Usher in Rabat.
At the trial, the defendants pleaded not guilty, with two of the nurses saying they had been tortured to extract false confessions, our correspondent says.
The defendants' Libyan lawyer said the infections were the result of poor hygiene and the reuse of syringes in the hospital.
Last year, the special court examining the case threw it out for lack of evidence, saying the only incontestable fact was that the children had died.
It is believed 23 have died so far.
But the seven defendants remained in custody, pending a referral to an ordinary criminal court.
The charges they now face in Benghazi still carry the death penalty.