UKRAINE’s President Volodymyr Zelensky has visited troops in the Kharkiv region, on the country's battered eastern front line.

It was his first official trip outside the Kyiv region since the Russian invasion began on February 24.

He was pictured in a bullet-proof vest surveying ruins in Kharkiv city.

Mr Zelensky told soldiers, "I want to thank each of you for your service." Later, he sacked the local security chief for "not defending" the city.

Russia has resumed shelling Kharkiv - Ukraine's second-largest city - in recent days after a fortnight of comparative quiet.

The city - Ukraine's second-largest - faced intense bombardment in the war's first months, with images showing tower blocks flattened to rubble.

Russian troops were gradually pushed back from its surrounding towns during April and May, prompting some who had fled Kharkiv to return, and the metro to reopen for the first time since the invasion.

But the city remains within range of Russian artillery. Several loud explosions were heard in the city after Mr Zelensky's visit.

President Zelensky's office posted a video on Telegram with the caption: "2,229 buildings have been destroyed in Kharkiv and the region. We will restore, rebuild and bring back life. In Kharkiv and all other towns and villages where evil came."

The president also visited the city of Kharkiv, which was bombarded day and night in the war's early months.

"In this war, the occupiers are trying to squeeze out at least some result," Mr Zelensky posted later.

"But they should have understood long ago that we will defend our land to the last man. They have no chance. We will fight and we will definitely win."

The president said he had fired Roman Dudin, the chief of the Security Service of Ukraine for the Kharkiv region "for the fact that he did not work on the defence of the city from the first days of the full-scale war, but thought only about himself".

"On which motives? The law enforcement officers will figure it out," he added.

Tuesday’s visit to Kharkiv is the first time President Zelensky has left the Kyiv region since the start of Russia's invasion.

He met the troops who have not just defended Kharkiv, but repelled the Russians, almost pushing them back to the international border.

The fact that he was able to visit shows just how much the tide has turned in Ukraine's second city. A few weeks ago, this morale-boosting visit would never have been possible.

But, do not be mistaken, Kharkiv is only safe for now. Elsewhere, Ukraine very much appears on the back foot, with Russian artillery barrages forcing troops to retreat in the Donbas.

With its charismatic president, Ukraine has very much won the informational war. Unfortunately for Ukrainians, that is not where this conflict will ultimately be decided.

The president met Kharkiv's mayor and the regional governor to discuss reconstruction plans, reportedly urging them to "find cool projects" to help rehabilitate the ravaged city.

"This is a chance for such districts to have a new face," Mr Zelensky said.