According to Lars Nylén, the general director of the prison service, there are three reasons for the increase in the use of isolation cells.
"More inmates, a different kind of crime based on networks, and their attempts to continue their criminal activities while they're in prison," he told Dagens Nyheter.
The result is that since 1995 the use of solitary confinement by prison officials has increased by 182%.
"It's no worse to isolate inmates who cause a disturbance than to isolate a diseased man who could infect others," said Nylén.
But while the general director's tough attitude will play well with critics who say that Sweden's prison system is too soft, renowned criminologist Jerzy Sarnecki argues that increased use of isolation cells is in nobody's best interests.
"Solitary confinement worsens the quality of criminal care," he said.
"Long term isolation is powerfully destructive. When you consider that many of those who are confined have psychological problems, the effects can be devastating."
Christer Karlsson, the chairman of the help organisation Criminals Return Into Society, agreed with Sarnecki, saying that solitary confinement "can break prisoners down, physically and psychologically".
But he also noted that there is an increase in voluntary isolation among prisoners who feel threatened.
That appears to support Lars Nylén's view that Swedish prisons are filling up with more hardened criminals than ever before.
And that, in turn, means that fewer are having their parole applications approved. In 1995 there were 62,541 approved applications, compared to 40,299 last year.
"A tougher clientele and more drug abusers in prisons increase the risk of misbehaviour and crime while on parole," Nylén told Dagens Nyheter.
"The easier prisoners consequently get a higher degree of freedom."