Vladimir Putin has ruled Russia as president or prime minister since the final day of 1999
Vladimir Putin has ruled Russia as president or prime minister since the final day of 1999 AFP

Russian President Vladimir Putin on Thursday urged Russians to vote for him at a "difficult" time for the country, hours before polls open and as Kyiv launched a barrage of deadly attacks on Russian border regions.

The former KGB agent is set to extend his rule by another six years this weekend in a presidential election the Kremlin says will show that the country is fully behind his assault on Ukraine.

Ahead of the vote, Kyiv has ramped up its aerial bombardment of Russian regions just across their shared border.

At least two people were killed and nine wounded in the Russian region of Belgorod Thursday, and the Russian national guard said it was fighting off attacks from pro-Ukrainian militias in Kursk -- the latest in a string of border clashes.

"I am convinced: you realise what a difficult period our country is going through, what complex challenges we are facing in almost all areas," Putin said in an address to Russians on the eve of the vote.

"And in order to continue to respond to them with dignity and successfully overcome difficulties, we need to continue to be united and self-confident," he added.

All of Putin's major critics are dead, in prison or exile and authorities blocked the few genuine competitors who tried to stand in the March 15-17 contest.

Alexei Navalny, Putin's most high-profile opponent over the last decade, died February in an Arctic prison colony.

He was serving 19 years for "extremism" -- charges widely seen as retribution for his campaigning against the Kremlin leader.

Kyiv has this week launched some of its most significant aerial attacks since the start of the two-year conflict.

The governor of Russia's Belgorod region, Vyacheslav Gladkov, said Thursday one person had been killed in an overnight drone attack.

A second aerial attack killed another woman and injured several more, he said in a post on social media, without specifying what weapons had been deployed.

Pro-Ukrainian paramilitaries also claimed to be escalating attacks and incursions in Russian border regions.

In a joint statement Thursday, three pro-Kyiv volunteer groups -- claiming to consist of Russians who oppose the Kremlin and have taken up arms for Ukraine -- called on authorities to evacuate civilians from the regions of Belgorod and Kursk.

"Civilians should not suffer from the war and any casualties in the process of fighting will be on the conscience of Starovoit and Gladkov," they added, referring to the regions' governors.

Russia has rejected the militias' claims to have gained ground.

The national guard said Thursday its units had beaten back "an attack by enemy diversion groups near the village of Tyotkino in the Kursk region".

The defence ministry said it had fended off another attack by Ukrainian forces trying to enter the Belgorod region via the village of Spodariushino, without saying when the clash had taken place.

It published video showing a series of air strikes on what it said was a Ukrainian sabotage group.

The fighting come just hours ahead of polls opening in Russia's Far East for the March 15-17 presidential election.

In power as president or prime minister since the final day of 1999, Putin has ushered in a sweeping crackdown of domestic dissent and an aggressive foreign policy

Victory will allow him stay in the Kremlin until at least 2030, longer than any Russian leader since Catherine the Great in the 18th century.

He called on Russians to use the election to show their unity behind his leadership.

"We have already shown that we can be together, defending the freedom, sovereignty and security of Russia," he said in a video message, flanked by flags of the Russian tricolour and the president's state insignia.

"Today it is critically important not to stray from this path," he said.

Early voting is already underway in occupied territories of Ukraine, and the vote will also take place in Crimea, the peninsula annexed by Moscow in 2014.

Kyiv says staging the election on Ukrainian territory is illegal.

Banners were unfurled sporting a red, white and blue 'V' logo -- an army symbol used as a sign of support for the military offensive.

Ukraine's foreign ministry on Thursday dismissed the vote as a "farce" and called on the international community not to recognise the results.

Russia's opposition has called for anti-Putin protests at midday on Sunday, the final day of voting.

Mobile voting stations have been set up in parts of Ukraine under Russia's control.
Mobile voting stations have been set up in parts of Ukraine under Russia's control. AFP
Ukraine: position of military forces
Ukraine: position of military forces AFP
In the Ukrainian city of Mariupol under Russian control, election officials opened pop-up polling stations
In the Ukrainian city of Mariupol under Russian control, election officials opened pop-up polling stations AFP
Vladimir Putin is set to secure another six-year term as Russia's president
Vladimir Putin is set to secure another six-year term as Russia's president AFP