Kyiv (Ukraine) (AFP) - Moscow said Monday its troops were battling a Ukrainian "sabotage" group that infiltrated Russian territory as Kyiv insisted it is still fighting for control of the flashpoint eastern city of Bakhmut.
The announcement of the latest incursion in the southern region of Belgorod came after Ukraine said Russian forces pummelled the eastern Ukrainian city of Dnipro with missiles and drones overnight.
Russian authorities said they had introduced an "anti-terror regime" in Belgorod, which has been attacked since the start of Russia's invasion of Ukraine in February last year.
A similar regime -- which gives special powers to security services and places a number of curbs on the public -- was in place in Chechnya between 1999 and 2009.
"In order to ensure the safety of citizens in the Belgorod region, the legal counter-terror regime has been introduced today," governor Vyacheslav Gladkov said.
He also said that at least six people were injured in an attack and most were in hospital with shrapnel and other wounds.
The Kremlin said President Vladimir Putin had been informed of the cross-border incursion, adding Moscow believed the attack was designed to "divert attention" from Bakhmut.
Gladkov said troops and members of the FSB security service were "taking the necessary measures to eliminate the enemy."
He said three people from the town of Graivoron received shrapnel wounds.
- 'Russia will be free' -
Members of the anti-Kremlin Freedom of Russia Legion claimed responsibility for the attack.
In a video released by a Telegram channel claiming to represent the group, a camouflaged spokesman, surrounded by armed men in fatigues, said: "Russia will be free!", using a slogan frequently used by Russian opposition activists.
"We want our children to grow up in peace and be free," the spokesman added.
The Telegram channel said that two settlements including Graivoron had been attacked.
Kyiv denied involvement.
"Ukraine is watching the events in Russia's Belgorod region with interest and is studying the situation, but has nothing to do with it," Ukrainian presidential advisor Mikhaylo Podolyak said.
Podolyak suggested that Russian "guerrilla groups" could be responsible.
"The only driving political force in a totalitarian country of tightened screws is always an armed guerrilla movement," he said.
After Putin sent troops to Ukraine, the border region of Belgorod has been repeatedly shelled, and dozens of people have been killed.
Authorities have also reported a series of incidents involving members of "sabotage" groups crossing over from Ukraine.
In April, the city of Belgorod was bombed by a Russian fighter jet which dropped ammunition over the city by accident.
'Fighting continues'
The attack was reported ahead of a widely-expected Ukrainian offensive, though President Volodymyr Zelensky has said his country is not yet ready.
Ukraine's army said earlier Monday that Russian forces pummelled Dnipro with 16 missiles and 20 attack drones overnight.
In the southern Kherson region, a 45-year-old man died when a shell fragment hit him in the heart, officials said.Two people also died in Russian attacks on the region of Donetsk over the past day, officials said.
Both Russian mercenary group Wagner and the regular army said over the weekend that Bakhmut had fallen, but Ukraine on Monday said its troops continued to fight for the devastated city.
Kyiv said it still controlled a small area of Bakhmut.
"The fighting continues," Ukraine's Deputy Defence Minister Ganna Malyar said, a day after Zelensky said Bakhmut was "not occupied" by Russia.
"The battle for the dominant heights on the flanks -- north and south of the suburbs -- continues," she added.
On Monday, Wagner chief Yevgeny Prigozhin, whose forces have spearheaded the grinding, months-long Russian assault on Bakhmut, said the mercenaries would leave the city by June 1 and hand over control to regular Russian troops.
Prigozhin said the mercenaries had set up "defence lines" on the city's western outskirts before a planned transfer of control to the Russian army.
Prigozhin has scathingly criticised Defence Minister Sergei Shoigu and Valery Gerasimov, Russia's chief of general staff, for blunders in Ukraine, accusing them of incompetence and causing large-scale losses.
Nuclear plant power cut
Following attacks on the region of Dnipro, Ukrainian authorities said that the occupied Zaporizhzhia nuclear power plant in the southeast went offline for several hours.
Ukraine's nuclear agency Energoatom said it was the seventh time the plant entered "blackout mode" since Moscow's troops took control in March 2022.
"The station is switching to power from the Ukrainian energy system," Ukrenergo, Ukraine's state grid operator, said later Monday.
The operator said that despite the morning attack Ukraine's energy system was operating in a "stable fashion" and that there was enough electricity to "cover the needs of consumers."
Located in the southeastern region of Zaporizhzhia, the six-reactor plant is the largest in Europe.