Ukraine staged a flurry of cross-border ground attacks with tanks and other armored vehicles and long-range drone strikes into Russia on Tuesday, assaults that appeared aimed at disrupting President Vladimir V. Putin’s re-election campaign messaging that the war had turned in Moscow’s favor.
Three armed groups of Russian exiles who operate in coordination with Ukraine’s military said they had crossed the border into southern Russia overnight and were fighting in border regions. Farther from the border, drone strikes hit a Russian oil refinery and fuel depot.
Throughout the war, Ukraine has struck targets inside Russia to disrupt military logistics, hit airplanes parked on runways and blown up railway bridges. The cross-border attacks, Ukrainian officials have said, are also intended to unnerve Russians and undermine Mr. Putin’s efforts to insulate them from the war.
Mr. Putin has through his two and a half decades in power — and through multiple elections, the next of which is scheduled to be held over the weekend — portrayed an image of bringing order to Russia. The Kremlin has also barred the only vocally antiwar candidate from running.
The reported border-area fighting in two regions, Kursk and Belgorod in southern Russia, could not immediately be independently confirmed.
The groups saying they crossed into Russia — the Free Russian Legion, the Russian Volunteer Corps and the Siberian Battalion — coordinate with Ukraine’s military. Some members of the groups, including the leader of the Russian Volunteer Corps, hold far-right nationalist views.
Members of two of the organizations, the Volunteer Corps and the Legion, also crossed into Russia last spring to skirmish with Russia’s border patrol and military. But whereas that incursion was considered to have a military purpose — diverting Russian forces to the border before a planned Ukrainian offensive elsewhere — the attacks on Tuesday delivered a more overtly political message.
A deputy commander of the Free Russia Legion, Maksimillian Andronnikov, posted a video on social media describing the incursion as being timed to the lead-up to a presidential election that is set to extend Mr. Putin’s tenure into a fifth term.
“We are the same Russians as you,” Mr. Andronnikov said in the address. “We also have the right to a statement of will.”
The group posted a statement on Telegram describing the cross-border assault from Ukraine as an effort to “take our land away from the regime, centimeter by centimeter.” Russians, it said, “will sleep freely, not be afraid of the doorbell, and will say what they think without fear. Russians will vote for whom they want, not for whom they should.”
The reports of the fighting in the border region coincided with Ukrainian drone attacks throughout central Russia, including a strike on an oil refinery near Nizhny Novgorod, east of Moscow. The refinery operator, Lukoil, said the facility had halted operations but did not clarify why. Another drone strike set on fire a fuel depot near the city of Oryol, south of Moscow.
Closer to the border with Ukraine, an exploding drone struck the City Hall in Belgorod, in southern Russia, the regional governor, Vyacheslav Gladkov, said in a post on Telegram. The attack wounded two civilians.
A spokesman for Ukraine’s military intelligence agency, Andriy Yusov, confirmed that Ukraine had launched the wave of long-range strikes, but he did not clarify their intention or confirm specific targets.
“Such incidents will occur with everything used for military purposes, one way or another,” Mr. Yusov told Radio Liberty. “This work will continue.”
The anti-Putin Russian groups posted videos they said were filmed inside Russia, showing tracked, armored vehicles driving in darkness through a forest and soldiers taking cover during a firefight.
A soldier with the Siberian Battalion posted a selfie video while lying in a forest saying, “Guys, there’s no need to vote at the elections with ballots, let’s vote with 7.62 caliber,” referring to a common caliber of bullets for Kalashnikov rifles. “Join the Siberian Battalion. Don’t be scared!”
The groups claimed to have captured a border village, Tetkino, in the Kursk region. “Putin’s army is rapidly abandoning the village,” the Legion said in a post on Telegram. The claim could not be independently verified.
In another setback on Tuesday for Russia’s military, an Il-76 military cargo plane carrying eight crew members and seven passengers crashed soon after takeoff in the Ivanovo region in central Russia, killing all aboard, state news agencies reported. The plane crashed after an engine caught fire, the news agencies reported.
Russian authorities denied the assault had breached the border. The Russian Ministry of Defense said its army soldiers and border guards had “disrupted an attempt by Kyiv to achieve a breakthrough on the territory of Belgorod and Kursk regions,” a state news agency, RIA, reported.
The Federal Security Service, a successor agency to the K.G.B. that includes the border guard service, said Russian forces had killed 100 soldiers and destroyed six tanks, 20 armored vehicles and a self-propelled artillery gun, Tass reported. The agency denied the attackers had entered villages inside Russia.
Ukraine has recruited exiled Russians from a strand of the Russian nationalist movement that years ago broke with Mr. Putin over immigration policies allowing Central Asian migrant workers into Russia, and over subsidies paid to ethnic minority regions in the North Caucasus after the Chechen wars of the 1990s.
Most prominent among them is the leader of the Russian Volunteer Corps, Denis Kapustin, who openly espouses far-right views and uses as his military call sign White Rex. German officials and the Anti-Defamation League have identified Mr. Kapustin as a neo-Nazi.
The Free Russia Legion operates as a unit in Ukraine’s International Legion, a force that also includes American and British volunteers and is commanded by Ukrainian officers. After the incursions last May, the Ukrainian military said no Ukrainian citizens crossed the border.
The assault Tuesday was the first known cross-border operation by the Siberian Battalion, a unit formed last year in Ukraine that draws from ethnic minority groups in Siberia, such as the Yakuts and Buryats.
It is a politically hued organization, Ukrainian officers have said, intended both to bring recruits into the fight against Russia inside Ukraine and to encourage rebellion by these ethnic groups inside Russia. Ukrainians have appealed for support from these groups over a shared history of cultural repression by Russia and over Moscow’s policies of recruiting heavily for its military operation in Ukraine from impoverished and politically marginalized ethnic minority regions in Siberia.
In interviews last fall, two recruits in the Siberian Battalion said they sympathized with the Ukrainian cause and wished to learn combat skills to apply at home in Russia. “I don’t consider myself Russian,” one soldier from Yakutia, who used the nickname Vargan, said. “I am not a traitor.”
Oleksandr Chubko and Ivan Nechepurenko contributed reporting.