Members of criminal gangs have sought to infiltrate Finland's prison staff, reports the daily Turun Sanomat.
Dozens of people involved in organised crime groups have sought jobs at penal institutions, it says. It remains unclear whether any have been successful.
The Criminal Sanctions Agency (Rise), which operates 26 prisons, relies on background checks by the Finnish Security and Intelligence Service (Supo).
Rise should take more responsibility for such checks, security researcher Jyrki Paasonen of the University of Eastern Finland told the newspaper.
"From Rise's point of view, Supo's current security investigation procedure is insufficient and causes problems, especially in relation to organised crime," said Paasonen.
Supo denies problems
According to the newspaper, Supo officials have expressed surprise at the criticism and denied any problems.
Late last year, Rise said that there was a shortage of guards at Finnish correctional facilities, and admitted that some employees lack required training.
In late 2020, Lännen Media reported that prison staff in Finland were subjected to systematic violence, with many prison guards targeted by assaults linked to organised crime.