Ukraine suffers setbacks in strategic city Severodonetsk

Ukrainian troops suffered setbacks after retaking parts of flashpoint eastern city Severodonetsk from Russian forces, local officials said on Monday, as the see-saw battle raged on for the strategically important city.

With Russia bringing the weight of its artillery to bear around Severodonetsk -- the largest city in the Lugansk region not under Russian control -- more help was promised from abroad.

The United Kingdom said it would follow the United States and send long-range missile systems to Ukraine, defying warnings from Russian President Vladimir Putin against supplying Kyiv with the advanced weapons.

Thousands of civilians have been killed and millions forced to flee their homes since Putin ordered Russian troops into Ukraine on February 24.

Fighting since April has been concentrated in the east of the country, where Russian forces have made slow but steady advances after being beaten back from other parts of Ukraine, including the capital Kyiv.

"Fighting is very fierce in Severodonetsk," regional governor Sergiy Gaiday told Ukraine's 1+1 television.

"Our defenders managed to counter-attack and liberate half of the city, but the situation has worsened for us."

Russian forces "are destroying everything with their usual scorched earth tactics" so that "there's nothing left to defend", he said.

Gaiday said on Sunday that Kyiv's troops had "cleared half of Severodonetsk and are moving forward", after Ukrainian forces earlier appeared on the verge of being driven out of the city.

- 'It's a horror show' -

Artillery strikes have intensified on Severodonetsk and neighbouring city Lysychansk, where pensioner Oleksandr Lyakhovets said he had just enough time to save his cat before the flames engulfed his flat after it was hit by a Russian missile.

"They shoot here endlessly... It's a horror show," the 67-year-old told AFP.

Lysychansk was among areas visited on Sunday by President Volodymyr Zelensky, who "got himself acquainted with the operational situation on the front line of defence", the presidency said.

In Moscow, Russian Foreign Minister Sergei Lavrov on Monday blasted European countries for blocking his plane from travelling to Serbia, saying: "The unthinkable has happened."

"This was a deprivation of a sovereign state of the right to carry out foreign policy," Lavrov told an online press conference in Moscow after several of Serbia's neighbours prevented his plane from passing through their airspace.

Lavrov had been due to hold talks with top officials in Belgrade, one of Moscow's few remaining allies in Europe since the launch of its military offensive in Ukraine.

Serbian daily Vecernje Novosti reported that Bulgaria, Macedonia and Montenegro had refused access to their airspace.

While Serbia has condemned Russia's military action in Ukraine, it has not joined the European Union in imposing sanctions in Moscow, despite its bid to join the bloc.

- UK pledges missiles -

Ukraine has asked supporting countries for ever more powerful arms to fend off the Russian attack, and its deputy defence minister stressed on Sunday this support was needed until Moscow was defeated.

The United States last week said it would supply Ukraine with advanced missile systems, the latest in a long list of weaponry sent or pledged to the pro-Western country.

But Putin said long-range missile supplies to Ukraine meant "we will draw the appropriate conclusions and use our arms... to strike targets we haven't hit before".

Unveiling the latest UK contribution, Defence Secretary Ben Wallace insisted Ukraine's Western allies must maintain their weapons deliveries to enable it to win.

The UK defence ministry said London had coordinated closely with Washington over its gift of the multiple-launch rocket systems, known as MLRS.

The M270 launchers, which can strike targets up to 80 kilometres (50 miles) away with precision-guided rockets, will "offer a significant boost in capability for the Ukrainian forces", the ministry added.

Western powers have imposed increasingly stringent sanctions on Russia but divisions have emerged on how to act, particularly on whether to engage in dialogue with Russia.

- Grain talks -

Russian troops now occupy a fifth of Ukraine's territory, according to Kyiv, and Moscow has imposed a blockade on its Black Sea ports, sparking fears of a global food crisis.

Ukraine and Russia are among the top wheat exporters in the world. Some 30 percent of the world's grain exports originate from the warring countries.

The United Nations said it was leading intense negotiations with Russia to allow Ukraine's grain harvest to leave the country.