It is getting more tense between two world powers, America and Russia.

Russia said on Friday that American special police, FBI planned to carry out a search of its San Francisco embassy.

The embassy is among the three that America ordered Russia to shut down on Thursday.

Russia's foreign ministry spokeswoman, Maria Zakharova said the search was set for Saturday and accused US authorities of threatening the "security" of Russian citizens and violating diplomats' immunity.

Meanwhile there was a twist in event on Friday as mysterious black smoke was seen rising from a chimney at the embassy, as firefighters confirmed its occupants were burning unidentified objects on the eve of the mission's closure.

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Washington ordered on Thursday that the facility and two others be shut down by Saturday in a retaliatory move after Russia demanded the US slash staff numbers at its Russian diplomatic missions.

The spat between the two nuclear-armed powers is another blow to US President Donald Trump's pledge to try to improve relations with Russia's Vladimir Putin.

Zakharova said in a statement that the FBI intended to carry out a search of the San Francisco consulate "including of the apartments of employees who live in the building and have immunity," forcing them and their families to leave for up to 12 hours.

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