STOCKHOLM -- Convicted spy Stig Bergling did not need a hacksaw to escape from Swedish prison. Knowing the liberal prison system, he simply walked away.

Bergling, 50, fled with his wife after being left unguarded during an overnight conjugal visit at his surburban Stockholm apartment Oct. 8. He had been serving a life sentence for selling defense secrets to the Soviet Union.

The escape further tarnished the image of the Swedish police and security forces, already under fire for their failure to catch prime minister Olof Palme's assassin 20 months after the murder. It also fueled debate about the penal system, where serious criminals often serve mild sentences in prisons that would put some hotels to shame.

Prime Minister Ingvar Carlsson, calling the affair "extremely serious," ordered a top-level investigation and canceled an overseas trip to monitor the chase.

"How could this happen?" asked opposition leader Carl Bildt. The escape "raises serious questions about the effectiveness of our system of justice and about the safeguarding of our national security."

Before resigning Monday over his department's handling of the affair, Justice Minister Sten Wickbom pledged to review a policy that allows prisoners to go home for as much as 72 hours every two months. "We must go to the bottom and change the system of leaves," he said, promising that those responsible would face "consequences."

Still, despite its tough talk, the Social Democratic government has given no indication it is prepared to back away from reforms adopted over the last 40 years that have geared the treatment of offenders more toward rehabilitation than punishment.

Wille Karlstrom, planning director of the National Prisons Board, said 41,000 leaves are granted annually to prisoners. He said less than 5 percent abuse the privilege.

Karlstrom said leaves "give the inmates the opportunity to maintain a social network and schooling in how to handle social and other problems."

The prisons are "up to a hotel standard," said Prisons Board official Tomas Pettersson. Each prisoner has his own cell, with a color television. Inmates bring their own VCRs and films. Pornography and violence are popular themes, he said.

Recently, prison authorities agreed to send a drug felon to Egypt for a nine-day excursion to help him reenter society. But public outrage led prison authorities to cancel the trip. In another case, Lt. Col. Bertil Strober, 55, demanded reinstatement in the Air Force upon his 1986 release after serving three years of a six-year sentence for espionage. The Air Force tried to fire him. But a court invalidated its action because the service missed a deadline for notice.

"This is absurd. What will the world think of us? We will have to pay him full salary until he retires in 10 years," said Air Force spokesman Gosta Edwards.

Earlier this year a man was sentenced to three years for torturing his 19-year-old fiance to death by electric shocks. After a public uproar, an appeals court stiffened the sentence to five years.

Critics say such lenient sentences encourage crime. A government crime prevention agency says violent crimes have tripled since the mid-1960s.

Bergling's espionage activity in the 1970s was so extensive it forced Sweden to revamp its defense system. When he was granted his first leave last spring to visit his 80-year-old mother, he was kept under close guard. This time he was accompanied by one unarmed guard, who checked into a hotel while Bergling stayed with his wife.

The next day the guard found Bergling gone. But a national alert was inexplicably delayed for 10 hours. Gunilla Arnerdal, the pipe-smoking warden of Norrkoping Prison, said Bergling had been an exemplary prisoner. "We supported him all we could. Now he has disappointed us," she said.

In 1984, Bergling changed his name to Eugen Sandberg. Authorities helped him keep it secret to make it easier for him to start a new life upon release.

Border police were unaware of Bergling's new name when the first alert was issued. An old photo distributed to border checkpoints further hindered the search.

The wife, who also changed her name to Sandberg, had rented three cars and taken a loan a few days before.