US federal agents inspected a Russian trade mission in Washington to confirm its closure on Saturday, despite a furious diplomatic protest from Moscow.
The United States and Russia are in the grip of a diplomatic dispute, and the trade representative's office is part of a group of properties Washington has ordered closed.
Russian officials were forewarned of the inspection and, according to a report in Foreign Policy magazine, lit a fire on Friday apparently to burn documents at the facility.
"Today, Russian Embassy personnel, together with State Department officials, walked through three properties in San Francisco, New York and Washington, DC that the Russian government is required to close," a State Department official said.
"These inspections were carried out to secure and protect the facilities and to confirm the Russian government had vacated the premises," he said, adding that all three are now closed.
On Saturday, US agents could be seen on the grounds of the Washington mansion, which served as both the home and office of the Russian trade representative. It has been owned by Moscow since the Soviet era.
The US State Department official said Washington had fully complied with its duties under the Vienna Convention in preserving the security of foreign missions, but in Moscow the Russian foreign ministry was furious even before the inspection began.
The ministry summoned acting US mission head Anthony Godfrey and gave him a "note of protest over the intention of the American authorities to conduct a search."
Russian news agency RIA-Novosti reported that the search began in the presence of Russian officials.
But the ministry nevertheless warned that the visit "could be used by the US intelligence services to organize an anti-Russian provocation involving planting compromising materials."
The trade mission in Washington is one of three diplomatic buildings -- including the consulate in San Francisco and an office in New York -- that the US had ordered Moscow to vacate by Saturday.
Russia's foreign ministry said Friday that US intelligence was also planning to search the consulate in San Francisco.
Black smoke was seen rising from a chimney at the consulate on Friday, and firefighters confirmed its occupants were burning unidentified objects.
A spokeswoman for the Russian foreign ministry insisted the smoke was due to measures to "preserve the building" at a time when officials were gearing up to leave.