Russian forces have taken control of the settlements of Soloviove in Ukraine's eastern Donetsk region and Kotliarivka further north in the Kharkiv region, the defence ministry says.
Ukraine's military made no mention of either locality in its evening General Staff report.
Kharkiv regional governor Oleh Syniehubov said on Monday that Kotliarivka, located near the town of Kupiansk, was one of several locations to come under Russian shelling.
But Ukrainian bloggers appeared to acknowledge that both villages were in Russian hands.
DeepState, a popular forum on the war, noted on Saturday that Kotliarivka had been captured by Russian forces and on Sunday said the neighbouring village of Kyslivka was also in Russian hands.
DeepState reported that Soloviove, northwest of the Russian-held town of Avdiivka, had been taken by Russian forces last week.
Russia has made slow but steady advances since taking Avdiivka in February, with a string of villages in the area falling to Russian forces.
Earlier on Monday, Russia warned the United Kingdom that if UK weapons were used by Ukraine to strike Russian territory then its forces could hit back at UK military installations and equipment both inside Ukraine and elsewhere.
Russia said UK 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 UK weapons to strike Russia.
The UK 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 the UK 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."
Cameron, during a visit to Kyiv last week, told Reuters that Ukraine had a right to use the weapons provided by the UK to strike targets inside Russia, and that it was up to Ukraine whether or not to do so.
The British foreign office spokesperson said on Monday Casey had also restated "the UK's position on providing support to Ukraine" in the meeting with Russian officials.
