People disguise as soldiers as they take part in a celebration marking the October Revolution of Russia in 1917, in St. Petersburg, Russia. File picture: Irina Motina/Xinhua

Moscow - A tip from US intelligence helped Russian security agencies thwart a bombing plot against targets in St Petersburg including Kazan Cathedral, the Kremlin said on Sunday.

Russian President Vladimir Putin telephoned US President Donald Trump to thank him "for information shared by the US Central Intelligence Agency (CIA) that helped trace, expose and detain a group of terrorists who had plotted explosions in St Petersburg's Kazan Cathedral and in other crowded places in that city," according to a statement carried by Russian state news agency TASS.

Putin vowed that Russian authorities would "swiftly and unconditionally" reciprocate if they obtain intelligence about plots against the United States, TASS reported.