Iran has sentenced two of the country's HIV researchers to prison for communicating with an "enemy government" and plotting to overthrow the state. Arash and Kamiar Alaei, who are brothers, underwent a half-day trial on 31 December in Tehran's Revolutionary Court. Kamiar was sentenced to three years in prison, and Arash to six.

The Iranian authorities notified the physicians' lawyer, Masoud Shafie, of the verdicts on 20 January. He has 20 days to appeal and intends to do so; the brothers say they are innocent.

The Alaeis were arrested last June, and their detention and trial were "unfair even by the draconian standards of Iran's penal code", says Jonathan Hutson, a spokesman for Physicians for Human Rights, based in Cambridge, Massachusetts.

Hutson points out that the six-month detention itself breached human rights, as Iran failed to meet its international legal obligations to explain the arrests, or to allow the men access to lawyers or the right to contest their detention before a judge.

And although Iranian law prohibits anyone from being detained for more than four months without charge, the state filed the charge of communicating with an "enemy government" only in December. Moreover, at the trial the prosecution indicted the men on new secret charges, now known to be the plot charges, denying them the right to defend themselves against these accusations and their right to due process.

The Iranian authorities claimed that the brothers had collaborated with scientists around the world, attended international AIDS conferences, and met with non-governmental AIDS organizations. "Those are not crimes — that's good medicine," says Hutson, arguing that the verdicts will have a chilling effect on academic collaboration between Iran and the rest of the world.

Julio Frenk, dean of the Harvard School of Public Health, echoed this concern on 15 January. The brothers' rights must be respected, he said, "so that they may continue their important work and so that all Iranian scientists and their international colleagues may feel secure about working together to solve the shared public health challenges of the world".

Last week, the state-run Islamic Republic News Agency cited an Iranian counter-intelligence official as saying that the brothers and two other unnamed individuals had confessed to working on behalf of the United States to overthrow the state, and that these statements would be televised. "Given interrogation techniques and duress known to exist in other cases like this one in Iran, any purported confession must be viewed as tainted and unreliable," says Hutson.