The Kremlin has sharply criticized the United States over the FBI's questioning of a Russian lawmaker in a New York airport amid strained ties between the two superpowers.

Kremlin spokesman Dmitry Peskov told reporters on October 7 that Moscow was 'deeply concerned' over the incident a day earlier, when Duma deputy Inga Yumasheva was questioned for an hour by the FBI upon her arrival in New York.

'This is highly disquieting information. Without a doubt, we are seriously concerned about it. We believe that such actions against a Russian deputy are unacceptable,' Peskov said.

State Duma speaker Vyacheslav Volodin, who called Yumasheva's questioning a 'cynical provocation,' said on October 7 that Yumasheva is expected back in Russia on October 8.

According to Russian officals, Yumasheva, who is in charge of coordinating relations between the U.S. Congress and the lower house of Russian parliament, had a visa and was in the United States to attend the Fort Ross Dialogue forum in California.

'She was asked to go to a separate room and an FBI officer, who introduced himself, started to question her, for an hour...,' the embassy said, citing Russian Ambassador Anatoly Antonov.

Relations between Russia and the United States have been severely strained over a variety of issues, including Moscow's aggression in Ukraine, its alleged meddling in the U.S. presidential election, and its involvement in Syria's civil war.

Last month the Kremlin accused the United States of violating its international obligations by failing to issue visas in time to some members of the Russian delegation to the UN General Assembly.