A researcher at the University of Amsterdam who helped produce a report on “Jihadi Brides” was an Islamic State “cyber-jihadist” herself, reports Dutch newspaper NRC Handelsblad.

Aysha Navest developed the study, “Chatting about marriage with female migrants to Syria”, alongside Annelies Moors, Professor of Contemporary Muslim Societies, University of Amsterdam, and Martijn de Koning, anthropologist, University of Amsterdam and Radboud University.

The paper presents an arguably sympathetic view of women who “see themselves as responsible for domestic life and attempt to normalise life under IS rule”, rejecting the so-called “tropes” of the jihadi bride who is either a victim of Islamist propaganda and online grooming by “unscrupulous men”, or a militant activist in her own right.

However, NRC claims to have uncovered evidence that Navest leads a double-life as an online “cyber-jihadist” herself, writing under the pseudonym “Ought Aicha” (Sister Aicha) on the Marokko.nl message forums.

The “Ought Aicha” account has made over 18,000 posts since 2006, many expressing Islamist sympathies. The account owner has expressed amazement at Muslims who dare to “criminalise” their brothers fighting for Islamic State, and praised Osama bin Laden “for protecting our Muslim community”.

A suicide bombing by an Islamic State fighter was dismissed as having only killed murtaddin (apostates) and Shi’ites (Muslims who follow a different branch of Islam than is practised in the Islamic State, which is Sunni).

NRC claims that Navest would not comment on whether the Marokko.nl account was hers, and her co-authors have stuck by their paper, claiming they saw no evidence of bias and that, in any case, “There are numerous examples of established anthropologists who are ideologically closely involved with their research or are themselves part of the research”.

A study by Europol last July indicated that “a significant percentage” of the thousands of European Union nationals recruited by jihadist groups in the Middle East are women.

They claimed 40 per cent of known Dutch recruits were female, compared with 20 per cent from Finland and Germany. The numbers for Belgium, Spain, and the UK were said to be similar.

Hundreds of British jihadists have now returned to the UK from the Middle East. It is estimated that just one eighth have been caught and convicted, and security experts warn that Britain’s “porous” maritime borders and “defenceless” small airfields provide such people with easy entry points.