Sir

We welcome Libya's recent decision to commute to life imprisonment the death sentences of five Bulgarian nurses and a Palestinian medic. All six were imprisoned for eight years on false charges of deliberately infecting children with HIV in the hospital where they worked. We also applaud the subsequent decision by Bulgaria's president to pardon and release the six immediately upon their extradition to Sofia.

We cannot accept, however, the Libyan government's continued denial of the scientific evidence in this case. That denial constitutes a barrier to establishing normal relations with the international medical and scientific community, from which assistance is urgently needed to upgrade Libya's health-care system.

The 17 July announcement that Libya's Higher Judicial Council had commuted the death sentence to life imprisonment should have been accompanied by an explicit acknowledgement that the real cause of the outbreak was an accident stemming from insufficient infection controls and hospital safety precautions.

Indeed, the statements from Libya's prime minister and foreign minister, condemning the recent pardon, reiterating the original conspiracy charges and calling for the health workers to be re-imprisoned, shows that the final judicial and political decision-making process had little to do with the accumulated scientific evidence.

Despite pleas from more than 100 Nobel laureates (R. J. Roberts et al. Nature 444, 146; doi:10.1038/444146a 2006), the judiciary refused to allow independent scientific evidence to be heard during the trial.

In particular, the judiciary failed to take into account convincing findings that the HIV infection was present in the hospital before the arrival of the health-care workers (T. de Oliveira et al. Nature 444, 836–837; 2006). Similarly ignored was the concurrent outbreak of hepatitis C among the same population of children — a strong signal that they were picking up other blood-borne infections from the hospital.

Opportunities for contamination of medical materials are frequent in many hospitals in developing countries, and there is an urgent need to redress this situation by improving health-care policies and practices. The Libyan government wants to upgrade the standards of hygiene and care in its hospitals. With the cooperation of the international scientific and medical community, it could make Libyan hospitals a model for health care in the region and in the African continent.

Removing the obstacle of Libya's intransigence on the science in this case is essential to allow such cooperation to move forward. We call on the Libyan authorities to put this affair behind them, and to exonerate the six health-care workers.