Russia warned Britain on Monday that if British weapons were used by Ukraine to strike Russian territory then Moscow could hit back at British military installations and equipment both inside Ukraine and elsewhere.
Russia said British Ambassador Nigel Casey was summoned to the foreign ministry for a formal protest after Foreign Secretary David Cameron said last week that Ukraine had the right to use British weapons to strike Russia.
Britain denied that Casey had been summoned, saying that he had met Russian officials "for a diplomatic meeting" in which he "reiterated the UK's support for Ukraine in the face of unprovoked Russian aggression".
Russia's foreign ministry said the Cameron remarks recognised that Britain was now de facto a part of the conflict and contradicted an earlier assurance that long-range weapons given to Ukraine would not be used against Russia.
"Casey was warned that in response to Ukrainian attacks on Russian territory with British weapons, any British military facilities and equipment on the territory of Ukraine and abroad" could be targeted, the Russian foreign ministry said.
The ministry said it considered Cameron's remarks a serious escalation.
"The Ambassador was called upon to reflect on the inevitable catastrophic consequences of such hostile steps by London and immediately refute the belligerent provocative statements of the head of the Foreign Office in the most decisive and unambiguous way."
@ISIDEWITH1mo1MO
What are the potential moral obligations countries have to each other when one is under attack?
