A Libyan court Thursday sentenced five Bulgarian nurses and a Palestinian doctor to death on charges they intentionally infected more than 400 children with the AIDS virus as part of an experiment to find a cure.

A sixth Bulgarian, a doctor, received four years in prison for changing foreign currency on the black market. He stood trial for infecting patients with AIDS, but his verdict did not mention that charge, and no explanation was given for the change.

Human rights groups have alleged that Libya concocted the experiment story to cover up for unsafe practices in its hospitals and clinics.

As soon as the sentence of death by firing squad was announced by Fadallah el-Sherif, the head of the five-judge panel that heard the case, five relatives of the infected children shouted: "Allahu akbar!" or "God is great!"

There was no visible reaction from the accused.

Under Libyan law, death sentences generate an automatic appeal.

"I thank God for this sentence," said Abdel Razek al-Odaibi, father of an infected child. "If there is a greater sentence than death, I would have wished it for them."

Al-Odaibi brought his 6-year-old infected son, Akram, to court. He was infected when he was 1 year old.

In Sofia, Bulgarian government spokesman Dimitar Tsonev said the verdict was "unacceptable."

"The verdict not only will be appealed, but we will make every possible effort to declare the medics not guilty," Tsonev said.

Irish Foreign Minister Brian Cowen told his Libyan counterpart, Abdul Rahman Shalghan, that the European Union has "serious concerns" about the fairness of the trial, EU spokesman Diego de Ojeda said.

"This is a very negative surprise for us," Ojeda said. "The European Union has assessed severe irregularities during the trial in terms of the rights of defense."

Cowen, whose country holds the EU presidency, met Shalghan at an EU-Mediterranean meeting.

Many relatives stood outside the packed court, holding pictures of Libyan leader Moammar Gadhafi and placards that read: "God is great" and "Long live justice."

Prosecutors demanded death sentences, accusing the defendants of intentionally infecting more than 400 children with HIV-contaminated blood (search) as part of an experiment to find a cure for AIDS. Twenty-three of the children reportedly have died of AIDS.

Some outside Libya have expressed skepticism over the allegations. Libya initially claimed the infections were part of a conspiracy by the CIA and Israeli intelligence, although it later backed away from those allegations.

Dr. Luc Montagnier (search), the French co-discoverer of the AIDS virus, testified that poor hygiene at the Benghazi hospital is likely to have led to the contamination. He estimated it happened in 1997 — more than a year before the defendants were hired to work there.

A commission of court-appointed Libyan doctors rejected his testimony, saying the defendants willfully infected the children with the virus through blood transfusions.

Libyan police arrested the defendants in 1999. In September 2002, a high tribunal in Tripoli acquitted them of conspiracy charges and handed the case over to an ordinary criminal court.

They were then placed under house arrest in Tripoli and detained again when their trial began in the eastern city of Benghazi (search) in September, according to Bulgarian media reports.

The EU, Amnesty International and other organizations have criticized the proceedings. Bulgarian Foreign Minister Solomon Pasi said the medics were tortured severely.

The defendants said they were jolted with electricity, beaten with sticks and repeatedly jumped on while strapped to their beds. Two of the women said they were raped.

The trial before the criminal court in Benghazi was nearing its conclusion when Gadhafi sought to end decades as an international pariah by renouncing weapons of mass destruction and opening his nuclear programs to international inspection.

Libya has also agreed to pay damages to relatives of passengers killed in the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, and the 1989 bombing of a French jetliner.

The moves have won Gadhafi suspension of many of the international sanctions imposed on his country for sponsoring terrorism.