Russia's President Vladimir Putin has thanked US President Donald Trump for intelligence that helped to foil attacks on Russian soil, the Kremlin said.

Mr Putin thanked his US counterpart "for the transfer, through special services, of information allowing the prevention of terrorist acts in Russia," the president's office said in a statement.

Russia's FSB, a successor to the KGB, quoted by Russian agencies, said two Russian citizens were arrested on Friday suspected of planning an attack in St Petersburg during the New Year festivities.

They appeared to have been preparing a "terrorist act", the reports said.

Although Moscow and Washington are at odds on many issues, both regularly stress their mutual determination to fight terrorism.