MOSCOW (REUTERS) - Russia's Defence Ministry said on Thursday (Aug 18) three MiG-31E warplanes equipped with Kinzhal hypersonic missiles have been relocated to its Kaliningrad region, Interfax reported.

Russian state-owned news agency RIA cited the ministry as saying that the MiG jets would be on round-the-clock duty.

Kaliningrad, a Russian Baltic coast enclave located between Nato and European Union members Poland and Lithuania, became a flashpoint after Lithuania moved to limit goods transit to the region through its territory, with Russia promising retaliation.

Tensions in the region have risen since Russia sent tens of thousands of troops into Ukraine six months ago in what it calls a "special military operation".

Earlier on Thursday, Finland's Defence Ministry said that two Russian MiG-31 jets were suspected of violating its airspace near the city of Porvoo, on the Gulf of Finland 150km from Russia.

US State Department spokesman Ned Price said Washington had seen the announcements from Russia regarding the repositioning of assets, which he said portrayed it as a matter of defence and deterrence.

"That of course is nonsense," Price told reporters.

"Russia does not face a threat from Nato. Russia does not face a threat from Finland. Russia does not face a threat from any other country."