Russia's Prime Minister Vladimir Putin said the Russian spies deported from the United States earlier this month had been betrayed.

In an extraordinary candid admission Mr. Putin told reporters on Saturday that 10 Russian agents arrested in the U.S. last month had been busted as a result of a “betrayal” and he knew the names of those who betrayed them. “This was the result of betrayal and traitors always end badly. They finish up as drunks, addicts, in the gutter,” he said.

Mr. Putin said he had met the Russian agents after their return to Russia and had sung Soviet-era patriotic songs with them. The undercover agents were swapped for four Russians who were serving prison terms in Russia for passing information to Western intelligence agencies.

Mr. Putin, a former KGB officer, said undercover spies live a hard life. “Imagine — they have to master a foreign language as your own, think and speak it, fulfill tasks in the interests of their motherland for many years without counting on diplomatic immunity,” he said.

The 10 Russians, many of who had lived in the U.S. for 10 years, had not been charged with espionage as none of them passed classified information, according to U.S. Attorney-General Eric Holder. They were accused of failing to register as agents of a foreign country — a charge they pleaded guilty to.

Asked whether the traitors would be punished Mr. Putin hinted that the Russian secret service may try to get its hands on them.

“Such issues are not decided at press conferences. But secret services live under their own laws. And all secret service officers know well these laws.”

Asked about the exposed spies' fate, Mr. Putin said:

“They will work in worthy places. I have no doubts that they will live interesting, bright lives.”

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