RUSSIA has launched a full-scale offensive in eastern Ukraine as the Kremlin aims to take control of the country’s industrial heartland.

Ukraine’s General Staff announced Vladimir Putin’s troops are focusing their efforts on taking full control of the Donbas region in a “new phase of the war”.

“The occupiers made an attempt to break through our defences along nearly the entire frontline,” the General Staff said in a statement on Tuesday.

The stepped-up assaults began on Monday along a front of more than 300 miles, focused on the Donbas regions of Donetsk and Luhansk, with the Russian forces trying to advance in several sections, including from the neighbouring Kharkiv region.

In southern Donetsk, the General Staff said the Russian military has continued to blockade and shell the strategic port city of Mariupol and fire missiles at other cities.

On Monday, Ukrainian President Volodymyr Zelenskyy said in a video address that a “significant part of the entire Russian army is now concentrated on this offensive”.

Moscow-backed separatists have been fighting Ukrainian forces for eight years in the mostly Russian-speaking Donbas and have declared two independent republics that have been recognised by Russia. Russia has declared the capture of the Donbas to be its main goal in the war since its attempt to seize the capital, Kyiv, failed.

“No matter how many Russian troops are driven there, we will fight,” Zelenskyy vowed. “We will defend ourselves.”

Troops battled in the streets of Kreminna on Monday before Russia was able to gain control of the city, according to Serhiy Haidai, Luhansk regional military administrator.

Haidai said that before advancing, Russian forces “just started levelling everything to the ground”. He said his forces retreated to regroup and keep fighting.

The breakthrough at Kreminna brings the Russians closer to the city of Slovyansk, which is seen as a key target in the Russian offensive. Slovyansk was seized by pro-Russian fighters in 2014, only to be retaken by Ukrainian forces months later following intense fighting.

Russian troops have already seized the city of Izyum, which sits north of Slovyansk, and they are poised to push toward the city from the north and the east. Slovyansk lies just north of another key city, Kramatorsk, where an earlier Russian attack on a train station killed more than 50 people.

The National: Ukrainian President Volodymyr Zelenskyy Ukrainian President Volodymyr Zelenskyy

On Monday morning, Oleksiy Danilov, secretary of Ukraine’s national security council, told Ukrainian media that the defensive line had not been broken elsewhere.

“Fortunately, our military is holding out,” Danilov said.

In Mariupol, Denys Prokopenko, commander of the Azov Regiment of the Ukrainian National Guard, said in a video message that Russia had begun dropping bunker-buster bombs on the Azovstal steel plant where the regiment was holding out.

The sprawling plant contains a warren of tunnels where both fighters and civilians are sheltering. It is believed to be the last major pocket of resistance in the shattered city.

Russia has Mariupol surrounded and has been fighting a bloody battle to seize it. If Russia takes Mariupol, it would free up troops for use elsewhere in the Donbas, deprive Ukraine of a vital port, and complete a land bridge between Russia and the Crimean Peninsula, seized from Ukraine in 2014.

In western Ukraine near the Polish border, at least seven people were reported killed on Monday in missile strikes on Lviv.

Lviv has been a haven for civilians fleeing the fighting elsewhere. And to the Kremlin’s increasing anger, the city has also become a major gateway for Nato-supplied weapons.

The attack hit three military infrastructure facilities and an auto shop, according to the region’s governor, Maksym Kozytskyy.

A hotel sheltering Ukrainians who had fled the fighting in other parts of the country was also badly damaged, Lviv Mayor Andriy Sadovyi said.

“The nightmare of war has caught up with us even in Lviv,” said Lyudmila Turchak, who fled with two children from Kharkiv in the east.

Kharkiv, Ukraine’s second-largest city, was hit by shelling on Monday that killed at least three people, according to Associated Press journalists on the scene.

Shelling could be heard overnight and into Tuesday morning in the major eastern city, which has been struck numerous times but remains firmly in Ukrainian control.

Moscow said its missiles struck military targets in eastern and central Ukraine including ammunition depots, command headquarters, and groups of troops and vehicles. It reported that its artillery hit hundreds of Ukrainian targets, and that warplanes conducted 108 strikes on troops and military equipment. The claims could not be independently verified.

General Richard Dannatt, a former head of the British Army, told Sky News that Russia was waging a “softening-up” campaign ahead of the Donbas offensive.

A senior US defence official, speaking on condition of anonymity to discuss the Pentagon’s assessments of the war, said there are now 76 Russian combat units, known as battalion tactical groups, in eastern and southern Ukraine, up from 65 last week. That could translate to around 50,000 to 60,000 troops, based on what the Pentagon said at the start of the war was the typical unit strength of 700 to 800 soldiers.

Meanwhile, it was reported the UK Government will soon send armoured missile launchers to Ukraine.

The Ministry of Defence demonstrated the Stormer High Velocity Missile (HVM) launcher for Ukrainians on Salisbury Plain two weeks ago, according to The Sun, with the paper adding the 13-tonne vehicles can be flown to the war on C-17 transport planes in days.

The Stormer is manufactured by BAE Systems, needs just three people to operate it and and uses Starstreak missiles, which can be used to take down low-flying aircraft.