STOCKHOLM — Stig Bergling, a former Swedish security officer who sold secrets to the Soviet Union during the Cold War and brazenly escaped while serving a life sentence for espionage, has died. He was 77.

Bergling's death was first reported Thursday by Swedish newspaper Dagens Nyheter. The Swedish tax authority, which records deaths, confirmed he died on Jan. 24. No cause was given.

Bergling, who worked for both the Swedish police security service and the military, turned over thousands of documents to the Soviet Union during the 1970s in one of Sweden's biggest spy scandals.

Among other things, Bergling gave Moscow details on the location of coastal defense sites and weapon systems, forcing neutral Sweden to revamp much of its defense system after he was caught in Israel in 1979.

After being sent back to Sweden he was sentenced to life in prison, but fled while on leave in 1987.

Bergling absconded during a conjugal visit with his wife, Elisabeth, in an apartment in suburban Stockholm. With police watching the entrance, Bergling fled through a back door. The couple took a ferry to Finland where authorities lost track of them.

His escape was a major embarrassment for Sweden's liberal prison system and prompted the resignation of the justice minister.

"It is every prisoner's duty to try to escape," Bergling told Swedish newspaper Aftonbladet in 2003, saying he had planned the escape for three years. He called his time on the run "the most exciting time of my life."

After reportedly living in the Soviet Union, Hungary and Lebanon, Bergling and his wife returned to Sweden in 1994, saying they were homesick. He went back to prison, but was released in 1997 after his life sentence was commuted.

Sven-Ake Hjalmroth, who headed Sweden's security service in 1976-1987, compared Bergling to Sweden's most notorious spy, Stig Wennerstrom, a Swedish air force officer who spilled secrets to the Soviets for 15 years.

"There is no doubt that these two were the most serious spy cases that we've had," Hjalmroth said.

"His legacy can't be a good one," Hjalmroth said of Bergling. "He was a mole in our operations and that's always serious in a security service."

Bergling remarried after his first wife died of cancer in 1997, but later divorced. In recent years he was diagnosed with Parkinson's disease and lived at an elderly people's home in Stockholm, according to Swedish news agency TT.

Information on funeral arrangements was not immediately available.

Stig Bergling, Soviet Spy Who Fled From Swedish Prison, Dies