One in five articles published in journals may contain faked data produced by unauthorised “paper mills” that are paid to fabricate scientific submissions, according to a study by German researchers who used new techniques to “red flag” problematic papers.

The study adds to the growing evidence that academic publishing faces a damaging surge in fabricated research sold by paper mills to researchers desperate for published work to boost their careers. It also backs up recent evidence that the majority of fake research comes from China.

The team, led by Professor Bernhard Sabel, who heads the Institute of Medical Psychology at Otto von Guericke University Magdeburg, found that the number of fake papers had risen substantially in recent years. Pressure to publish had been particularly intense in China, they said; for example, some Chinese hospitals and health authorities require physicians to be first author on a set number of papers.