Soviet Plan to Assassinate Tito Told : Europe: Secret service had assigned an agent to kill the former Yugoslav leader, a senior Yeltsin adviser says. The murder was never attempted.

Soviet agents planned to assassinate former Yugoslav leader Josip Broz Tito in the 1950s using lethal bacteria or a poisoned jewel box, a senior adviser to Russian President Boris N. Yeltsin said.

The murder of Tito, who was a thorn in the Soviet Union’s side, was never actually attempted.

But the forerunner of the KGB devised elaborate plans for the killing and even chose the assassin, a Soviet spy who had become Costa Rica’s ambassador to Yugoslavia, Dmitri Volkogonov wrote in Thursday’s Izvestia.

Volkogonov is a prominent historian and retired general who serves as Yeltsin’s military adviser. He has been an active researcher in formerly secret Soviet archives and is co-chairman of the joint U.S.-Soviet committee searching for American prisoners of war in the former Soviet Union.

The agent who was assigned to kill Tito had previously helped arrange the brutal murder of Leon Trotsky, dictator Josef Stalin’s bitter enemy, in Mexico in 1940. His real name was Iosif Grigulevich, and his code name was Max, according to Volkogonov.

Tito was a Soviet ally during World War II, when he led the Yugoslav resistance to Nazi Germany. He established a Communist government in Yugoslavia in 1945 but stopped obeying Moscow’s orders three years later, enraging Stalin.

Stalin’s secret police chief Lavrenti Beria ordered his agents to kill the renegade Yugoslav leader. They turned to the agent known as Max, who had won the confidence of Costa Rican leaders and obtained the post of ambassador to both Yugoslavia and Italy.

The Soviet security ministry considered having Max release lethal plague bacteria at one of Tito’s diplomatic receptions, according to a secret memo quoted in Volkogonov’s article.

“The death of Tito and every other person in the room would be guaranteed,” the memo said. “Max himself would not know anything about the nature of the substance. To save his life, Max would be immunized against plague beforehand.”

Other options devised included shooting Tito with a “silent mechanism disguised as a personal article” such as a pen, lighter, cane or briefcase.

Finally, the security ministry proposed in the memo to construct a beautiful jewel box that would emit a deadly gas when opened.