The governor of Russia's Belgorod region has accused "a sabotage and reconnaissance group" from Ukraine of crossing the border to carry out an attack on Monday.

Three people were injured, Belgorod Governor Vyacheslav Gladkov said, adding that three homes and one administrative building were also damaged.

However, Ukrainian presidential advisor Mykhailo Podolyak said Kyiv had "nothing to do" with the attack and said Russian anti-Kremlin guerrilla groups were responsible.

"Ukraine is watching the events in the Belgorod region of Russia with interest and studying the situation," he said.

The alleged incursion would be the largest attack of its kind since Russia invaded Ukraine in February 2022.

Gladkov said that Russia's military and FSB state security service were "taking the necessary measures to eliminate the enemy" but did not disclose further details.

The claims come after footage purportedly showing a Ukrainian tank attacking a Russian border post was shared by the Baza Telegram channel, which is linked to Russia's security services.

What Russia has said about the Belgorod incident

Kremlin spokesperson Dmitry Peskov said Russian President Vladimir Putin had been informed about the incident.

He claimed the attack was an attempt to "divert attention" away from Bakhmut and "minimize" Ukraine's losses in the eastern city, which Moscow claims to have captured but which Kyiv says is not completely occupied.

Peskov said no evacuation was underway but later Governor Vyacheslav Gladkov said authorities were helping people leave the area under attack.

"The situation here continues to be extremely tense," Gladkov said, adding that authorities were going door to door to notify local residents. "I hope that our military will complete their task in the nearest future."

Ukraine blames attack on Russian citizens

Ukrainian military intelligence blamed the attack on Russian citizens belonging to two paramilitary groups, the Freedom of Russia Legion and the Russian Volunteer Corps, local media reported later on Monday.

"I think we all can only welcome the decisive actions of opposition-minded Russian citizens, who are ready for an armed struggle against the criminal regime of Vladimir Putin," Ukrainian military intelligence spokesperson Andriy Yusov was quoted as saying.

A Twitter account claiming to belong to the Freedom of Russia Legion said the group had "completely liberated" the border town of Kozinka and its forward units had reached the district center of Graivoron.

"Moving on. Russia will be free!" it wrote.

The Belgorod region borders Ukraine and has been shelled several times since Russia invaded its neighbor in February 2022.

In April 2023, a Russian fighter jet accidentally dropped a bomb on Belgorod, damaging several buildings in the regional capital of the same name.

zc/wd (Reuters, AFP, AP)