Fresh evidence that senior officials in the Iranian government have co-authored scientific papers that show signs of plagiarism came to light this week (see page 704). This follows similar revelations in October (see Nature 461, 578–579; 2009).

The first wave of alleged plagiarism cases was widely discussed both inside and outside Iran, and provoked dismay among the country's researchers and reformist bloggers. The cases were also reported by Iran's mainstream media, which deserve credit for airing the story despite the present regime's record of shutting down newspapers, arresting journalists and otherwise intimidating free inquiry.

The regime's research institutions, however, have done little to investigate the allegations. This is perhaps not surprising, given the extreme political sensitivity of the accusations. One of the disputed papers was co-authored by transport minister Hamid Behbahani, who supervised President Mahmoud Ahmadinejad's PhD. Other questionable papers were co-authored by science minister Kamran Daneshjou, who oversaw this year's disputed presidential election. An official investigation is needed to clarify the circumstances of these and the new cases of alleged plagiarism. Senior scientists also have a responsibility for what happens in their labs, and for papers on which their names appear.

One can only speculate over what might cause such plagiarism. In some cases, using texts to help counter a poor command of English may provide extenuating circumstances. And in Iran, as in several developing countries, there is a cultural expectation that officials should have strong academic credentials. This could tempt weaker academics to inflate their publication record, perhaps by plagiarism. It can also lead to other types of academic fraud: in November 2008, the late Ali Kordan was impeached by the Iranian parliament and removed as interior minister after he admitted that his honorary law doctorate from the University of Oxford was fake.

Another factor could be the politicization of Iran's research system. After the 1979 Islamic revolution, universities were purged of perceived Western influences and staff. Many of the best scientists left the country. The Iranian research enterprise began to recover in the late 1990s under reformist president Mohammad Khatami — academic appointments were more often based on merit, and the country's research output improved in both quantity and quality. But the research environment has deteriorated since Ahmadinejad took power in 2005, as his regime has exerted political influence over promotions within universities. And in the aftermath of this summer's protests over the election, Iran's universities have become a hotbed of opposition — a prime focus for the government's crackdown. The regime now says that it intends to reinforce Islamic values across academic staff and courses, which many scientists take as code for further repression.

Leading researchers inside Iran are keeping their heads down. But many are quietly pressing for the authorities to investigate the plagiarism allegations, which, they note, would be consistent with wider demands by academics for the current regime to be more accountable and respectful of the republic's values and civil rights. They are also pushing for merit-based promotion practices, and are having some success in persuading Iran's academic institutions to emphasize ethics in the practice of research and publishing.

Iran's researchers, both inside and outside the country, are to be applauded for their defence of excellence and scientific integrity in such difficult political conditions. The actions of a few must not be allowed to soil the reputation of the majority of Iran's scientists. Rather, the international scientific community must redouble its efforts to support and collaborate with its Iranian colleagues.