A former US embassy employee is being held in Moscow, according to the Russian state news agency.

Robert Shonov, identified as a former employee of the US Embassy in Russia, was arrested in the Russian city of Vladivostok and charged with conspiracy, This is reported by the Russian state news agency Tass.

Vedant Patel, a spokesman for the State Department, told reporters at a briefing on Monday that he had seen the report but that “I have nothing additional to offer at this time.”

Tass, citing an anonymous law enforcement official, said Mr Shonov was charged with “cooperating on a confidential basis with a foreign state or international or foreign organization”. He has been taken to Moscow’s Lefortovo Prison, Tass reported, and no court date has been set.

Seclusion is normal in Lefortovo, a notorious high-security prison that currently houses Evan Gershkovich, the Wall Street Journal correspondent who was charged with espionage in March, allegations his employer and US officials have vehemently denied. The prison also holds Paul Whelan, a former U.S. Marine serving a 16-year sentence on what the United States claims is trumped-up espionage charges.

In the Soviet era, the KGB held Soviet dissidents in prison, and more recently it has been used to isolate Kremlin opponents.