Russia bombed a residential building in the Ukrainian city of Kharkiv on Saturday, killing three people and wounding more than 50 as it stepped up renewed hostilities. 

Officials said four guided bombs hit Ukraine's second-largest city, located near the Russian border, and President Volodymyr Zelensky posted footage of the torn-off facade of an apartment block and a crater outside.

"Russian terrorists have again hit Kharkiv with guided bombs," he wrote on Telegram, announcing three dead as rescuers  searched the rubble.

Fifty-two people were wounded in the strikes, including three teenagers, the regional prosecutor's office said.

Regional governor Oleg Synegubov had said earlier that "Doctors are fighting for the lives of four patients -- two women and two men, who are in serious condition". 

He posted photos of blown-out windows and cars and a minibus damaged by the blast, which tore through the walls of flats, leaving tangled wreckage and rubble. 

Rescuers worked with dogs, cutting through doors and dousing a fire in the flats near the city's central bus station.

Bodies in bags were laid on the ground outside, an AFP journalist saw. One dead woman lay at a bus stop, wearing bright sandals, her bag by her side. 

An elderly woman with blood running down her face and legs was helped onto a stretcher as she protested she did not want to go to hospital.     

Synegubov said "only civilian infrastructure was damaged".

"Since the beginning of this June alone, Russians have used more than 2,400 guided aerial bombs against Ukraine already, about 700 of which were targeted at the Kharkiv region," Zelensky said in a later statement.

"This is calculated terror."

New weaponry

Russia launched a new offensive in the region in May, taking significant territory, and has increasingly targeted Kharkiv.

In May, a guided bomb attack on a hardware store killed 16 and wounded dozens. 

Defence Minister Rustem Umerov said last month that Russia has dropped almost 10,000 guided bombs on Ukraine this year.

Prosecutors said Russia used its new UMPB D-30 SN guided bombs for the latest attack on Kharkiv, launched from the Belgorod region bordering Ukraine.

Russia's Rossiiskaya Gazeta newspaper wrote this month that the weapons are now being used in the Ukraine war.

They can be fired from the ground at long range as well as from planes, it wrote, which means "it is almost impossible to anticipate" an attack.

"This Russian terror with guided bombs must be stopped and can be stopped. We need strong decisions from our partners so that we can destroy Russian terrorists and Russian combat aircraft where they are," Zelensky said.

Russia also launched 16 cruise missiles and 13 attack drones at energy infrastructure in several regions overnight, Ukraine's military said. 

This was Russia's "eighth massive, combined attack on energy infrastructure facilities" in three months, the energy ministry said.

More than two years into the Russian invasion, missile and drone attacks have crippled Ukraine's electricity generating capacity and forced Kyiv to impose blackouts and import supplies from the European Union. 

Russia said its troops "carried out a group strike with long-range high-precision weaponry from air and sea and also drones on Ukrainian energy facilities that power arms production". 

The defence ministry said strikes targeted stores for munitions and "air-launched weapons provided to the Ukrainian military by western countries". 

"All the set targets were hit," the ministry said, justifying the strikes as retaliation for Ukrainian attacks on Russia's energy network. 

Ukraine's energy ministry said energy facilities in the southern Zaporizhzhia and western Lviv regions were damaged.

Russian attacks have destroyed half of Ukraine's energy capacity, according to Zelensky.

Shelling deaths

In Zaporizhzhia, Russian artillery shelling also killed one civilian, according to the regional military administration, while a policeman manning a checkpoint was killed by a drone in the southern Kherson region, police said.

Five civilians were killed by shelling in frontline areas of the Donetsk region, regional head Vadym Filashkin said.

Frontline clashes were reported near the towns of Pokrovsk and Toretsk, where Moscow "continues to increase the pace of offensive actions, deploying significant forces," Kyiv's military said.

Russia's defence ministry said troops had improved positions in the Donetsk, Lugansk and Kharkiv regions.

The head of Russian authorities in the Donetsk region, Denis Pushilin, said the region had come under attack from Ukraine.

Three men working for a construction firm were killed by cluster munitions, he said.

In Russia's southern Belgorod region, a man was killed in the shelling of a farm near the border, said governor Vyacheslav Gladkov.