Libya has sentenced five Bulgarian nurses and a Palestinian doctor to death by firing squad for deliberately infecting some 400 children with HIV.
Experts backed the medics' defence that poor hygiene was to blame
Prosecutors demanded the death penalty, claiming the accused gave patients HIV in a bid to find an Aids cure.
The medics, who worked at a children's hospital in the city of Benghazi, were arrested five years ago.
Bulgaria's government, which had been lobbying for their release, condemned the "unfair and absurd" verdicts.
The Libyan court found the six health workers guilty of having caused the death of 40 children and of infecting almost 400 others with HIV.
Another Bulgarian, Dr Zdravko Georgiev, was initially reported to have received the death penalty but has in fact been given a four-year sentence and may be released soon, Bulgaria's ambassador to Libya said.
Nine Libyans who worked at the same hospital were acquitted.
The courtroom in Benghazi was surrounded by 100 armed police, Bulgaria's BTA news agency reported.
MEDICS GIVEN DEATH PENALTY
Kristiana Vulcheva - nurse
Nasya Nenova - nurse
Valya Chervenyashka - nurse
Snezhana Dimitrova - nurse
Ashraf al-Hajuj - doctor
Source: BTA news agency
Inside it was packed to capacity, with 15 foreign diplomats among those attending the session which was the culmination of a trial stopped and started several times over the years.
At one point, the Libyan leader, Colonel Muammar Gaddafi, had accused the health workers of acting on orders from the CIA and the Israeli secret service, Mossad.
Libya later rowed back on this allegation.
The medics had always protested their innocence and said they had been tortured by the police, with daily beatings, sexual assault and electric shocks.
They called expert witnesses, including one of the team which discovered the Aids virus, who said this was an epidemic caused by poor hygiene at the hospital, not by any international conspiracy.
Western diplomats say the prosecutions arose because the authorities simply needed someone to blame for a tragedy which caused outrage in Libya.
With Col Gaddafi recently moving to improve Libya's international standing, Bulgaria had hoped the court would be lenient.
Gaddafi's Libya has not executed anyone in nine years
"I'm shocked by the verdicts...We're not going to accept them," said Bulgarian Justice Minister Anton Stankov.
The government in Sofia is calling for a strong reaction from the international community.
The European Union has already voiced its extreme concern.
Bulgaria's parliamentary speaker, Ognyan Gerdzhikov, said he was confident the death sentences would not be carried out.
"I expect Gaddafi to act like a humanist to win certain political credit, which he needs from public opinion," he told Bulgarian radio.
But relatives of the infected children were celebrating.
"The verdict is fair. What they did is a crime against humanity. They planted a bomb inside our children," Ramdane Ali Mohamed, whose sister died of Aids, told Reuters.