Moscow says Ukrainian saboteurs opened fire against civilians on Russian territory, a claim Kyiv denies.

President Vladimir Putin has said Russia was hit by a “terrorist attack” in the southern Bryansk region bordering Ukraine, and vowed to crush what he said was a Ukrainian sabotage group that had fired at civilians.

Moscow said the Ukrainians had crossed the frontier, fired on a car killing one person and wounding a child, and held hostages in a shop.

Ukraine accused Russia of staging a false “provocation”, but also appeared to imply some form of operation had indeed been carried out by Russian anti-government partisans.

Senior adviser to Ukrainian President Volodymyr Zelenskyy, Mykhailo Podolyak, said on Twitter: “The story about [the] Ukrainian sabotage group in RF [Russian Federation] is a classic deliberate provocation.”

He said Russia should “fear your partisans”. A day earlier, after apparent attempted drone attacks on Russia, which Moscow blamed on Ukraine, Podolyak had responded in a similar manner, suggesting attempts at domestic assaults.

The story about 🇺🇦sabotage group in RF is a classic deliberate provocation. RF wants to scare its people to justify the attack on another country & the growing poverty after the year of war. The partisan movement in RF is getting stronger & more aggressive. Fear your partisans…

— Михайло Подоляк (@Podolyak_M) March 2, 2023

Amid reports of shelling and sporadic sabotage, Russia’s border regions have become increasingly volatile since Moscow invaded Ukraine a year ago in what it called a “special military operation”.

Putin, in a televised address, said: “They won’t achieve anything. We will crush them”.

The group was made up of the kind of people who wanted to rob Russia of its history and language, he said.

RIA news agency quoted Russia’s Federal Security Service (FSB) as saying the situation was under the control of law enforcement agencies. It said a large number of explosive devices had been found and demining was taking place.

In two videos circulating online, armed men calling themselves the “Russian Volunteer Corps” said they had crossed the border to fight what they referred to as “the bloody Putinite and Kremlin regime.”

Describing themselves as Russian “liberators”, the men called on Russians to take up weapons and rise up against the authorities. They said they did not open fire on civilians.

Al Jazeera could not immediately verify the authenticity of the videos.

Kremlin spokesman Dmitry Peskov told reporters that Putin was being briefed by security chiefs.

Pavel Felgenhauer, a Russian military analyst, told Al Jazeera: “It seems right now a rather strange story; the Ukrainians say it’s not them, and Russians say it’s them.”

Despite the incident, he said, it is currently not significant enough for Russia to begin a new offensive or be used in any “pretext situation”.

“There have been reports of Ukrainian spies and agents being arrested in different places and being armed, so this is not that much out of the normal, so to speak,” Felgenhauer said.

“This is not a kind of Ukrainian invasion with tanks or anything; this is a report of a group of armed men, apparently.”