A Russian banker accused of participating in a Cold War-style spy ring pleaded guilty Friday to conspiracy.

Evgeny Buryakov pleaded guilty to conspiring with others to act as an agent of a foreign government without registering with the U.S. government. Prosecutors said that from 2012 through January 2015, he teamed up with diplomats to gather sensitive economic intelligence on potential U.S. sanctions against Russian banks and on U.S. efforts to develop alternative energy resources.

Buryakov had previously pleaded not guilty to conspiracy and other charges alleging he purposely failed to register as a foreign agent to conceal his true role as a covert operative embedded at a Manhattan branch of Vnesheconombank, or VEB.

He remains behind bars until sentencing, which was scheduled for May 25. Prosecutors and the defendant agreed as part of the deal that a 30-month sentence is appropriate.

The defense previously had argued that laws exempted Buryakov from registering because he already was a visa-carrying official with a financial institution that is an arm of the Russian government.

The government said Buryakov had obtained a work visa by lying on paperwork and saying he wouldn't commit espionage.

The case was announced less than five years after the arrest of 10 covert agents — a sleeper cell referred to as "The Illegals" by the SVR, the foreign intelligence agency headquartered in Moscow — who led ordinary lives for several years in the United States using aliases. All 10 pleaded guilty in federal court in Manhattan to conspiracy charges and were ordered out of the country as part of a spy swap for four people convicted of betraying Moscow to the West.

Before his arrest, Buryakov lived in the Bronx with his Russian wife and two children.