Exeter prison is still not doing enough to address high levels of drug use and violence, according to a new report.
Last year the prison was told to take immediate steps to improve amid concerns about the safety of inmates.
But today inspectors say there has been an 'inexplicable failure' to implement a new strategy.
A prison spokesman said they accept more needs to be done and steps are being taken to stop drugs getting in.
In the first of its new ‘Independent Reviews of Progress’ (IRPs), Her Majesty's Inspectorate of Prisons examined 13 recommendations from last year's inspection.
The new report presents a mixed picture, with a "lack of progress" in more than half of the recommendations.
In the May 2018 inspection, inspectors found there had been six self-inflicted deaths between 2016 and 2018 and self-harm had risen by 40 per cent.
The Government is understood to be in the process of recruiting a specialist drugs lead for the South West, who will support HMP Exeter’s efforts to reduce drug use.