A Palestinian-born doctor jailed in Libya for allegedly infecting children with HIV has filed a suit for torture against Libyan leader Muammar Gaddafi.
Dr Alhajouj and his colleagues were freed in July
Ashraf Alhajouj, imprisoned with five Bulgarians for more than eight years, filed the suit through a French group.
The move coincides with a visit to France by Mr Gaddafi, which enabled the group to invoke an international anti-torture convention against him.
It is unclear how far the action can go as Mr Gaddafi has diplomatic immunity.
French President Nicolas Sarkozy and his then-wife Celia have been credited with brokering the release of Mr Alhajouj and the other medics on 24 July.
But questions were raised about the terms of the release after Mr Sarkozy signed major trade agreements with Libya the following day.
France is the first Western country to invite Mr Gaddafi for an official visit, but on Tuesday opposition MPs boycotted a meeting with him at the French parliament.
Immune from prosecution
The French charitable organisation Lawyers Without Borders filed the action against Mr Gaddafi, five senior Libyan police officers and a Libyan doctor.
Francois Cantier, president of group, said Mr Gaddafi's 400-strong delegation should be investigated.
"It is possible that these people are in the delegation and we are asking that this be checked," he told the BBC News website.
Mr Sarkozy has sought constructive dialogue with Mr Gaddafi
The case cites a 1984 convention allowing national authorities to initiate legal action against anyone visiting the country who is suspected of torture.
But Mr Gaddafi has been immune from prosecution in France since 2001, when the country's top court ruled that as a head of state he could not face legal action over the bombing of a French passenger jet in 1989 in which 170 people died.
Mr Cantier said he did not want to let Mr Gaddafi's visit to France pass without the case of the medics being brought to public attention.
"Our suit also has a symbolic value, since we know that [Mr Gaddafi] was at the origin of this situation... nothing in Libya can happen without Gaddafi."
The medics were convicted of deliberately injecting 438 children with HIV-tainted blood. Fifty-six of the children have since died.
The six, who were jailed in 1999, have always proclaimed their innocence and say they were tortured to confess.
They initially faced the death penalty before their sentences were commuted to life imprisonment.
In an interview for Dutch TV after his release, Dr Alhajouj said the Libyan authorities had drugged him and attached electrodes to his feet and genitals.
Police dogs were set on him, and he was later forced to pretend that he had been treated well, he said.
Mr Gaddafi's son, Saif al-Islam Gaddafi, has also said the medics were tortured.