Moscow: Vitaly Shlykov, a former Soviet intelligence agent who spent years in a Swiss prison after being convicted of espionage and later became an internationally known military analyst, has died at 77.

Shlykov died of a heart condition over the weekend at his apartment in Moscow, the Council for Foreign and Defense Policy confirmed on Monday. Shlykov was one of the founders of the council, which advises the Kremlin on security issues.

Following his retirement from Soviet military intelligence in 1988, he served from 1990 to 1992 in the government of Russia's first president, Boris Yeltsin, as deputy head of a committee for public security.

In more recent years, Shlykov helped engineer a radical reform of the Russian military to shed its Cold War legacy and turn it into a modern force.

Shlykov joined Soviet military intelligence in 1958 after graduating from Moscow's Institute of International Relations. He served for 30 years in the Main Intelligence Directorate of the Russian General Staff, known under its Russian acronym of GRU.

During his GRU career, he worked as a senior analyst specializing in assessing the military industries of the United States and other Western nations. He made frequent trips to the West on a false American passport.

One of his duties was to maintain contacts with Dieter Felix Gerhardt, a senior officer of the South African Navy who was working as a Soviet spy. In January 1983, Shlykov was arrested on a trip to Zurich while carrying the equivalent of about $100,000 in cash to hand over to Gerhardt's wife, who was supposed to serve as a liaison.

Soviet intelligence was unaware that Gerhardt and his wife had been arrested a few weeks earlier and had told interrogators about the meeting in Switzerland.

Realising after the arrest that his cover had been blown, Shlykov claimed he was a Soviet citizen who had emigrated to the West - another false identity he was supposed to offer in just such a case.

He never revealed his true identity to the Swiss police, and in 1984 was convicted of espionage and sentenced to three years in prison. He was released early for good behavior and returned to the Soviet Union in 1986.

After his retirement two years later, he became a prominent scholar specializing in military policy and wrote extensively on security issues.

Shlykov strongly backed the Kremlin's military reform, intended to radically cut the bloated and inefficient Russian military and turn it into a more modern and agile force. His support contrasted sharply with that of many other military veterans, who insisted the reforms were destroying the military.

In a 2010 interview with The Associated Press, Shlykov described the effort as "the most radical reform of the Russian military in 150 years" and said it should make the armed forces more capable.

Shlykov first spoke to the media about his espionage experience two decades after quitting the service.

"During my life span, I have lived several lives, full of tension and excitement," he said in a 2006 interview with Radio Liberty.

He is to be buried on Tuesday at Troyekurovsky Cemetery.