AIM-listed companies have been accused of having their “head in the sand” when it comes to ensuring gender diversity on company boards after new research revealed representation to have stalled.

The number of women holding directorships in AIM companies remained at one in six over the last year, according to an annual gender diversity report from Addidat and Indigo Independent Governance.

FTSE 350 firms have a voluntary target of 40 per cent female board representation, which the study found only 11 per cent of AIM-listed companies would currently hit.

Meanwhile, the number of all-male boards on London’s junior stock market increased, with 38 per cent having no female directors.

Indigo founder Bernadette Young said the results were “disappointing” and AIM companies “need to consider adopting clearer diversity ambitions”.

“Gender diversity transformed over the last few years in the FTSE 350 and reporting has been a big driving factor,” Young told City AM.

She called for transparent search and selection processes to “eliminate unconscious bias”.