But in a bit of much-needed positive news for Kyiv, its military claimed to have "partially pushed back" their enemy from the border town of Vovchansk in the northeastern Kharkiv region, where Russia last week launched its fresh offensive.

In an update on the battlefield situation, Ukraine's military said active combat clashes raged on in the north and northwestern parts of the town and a total of 18 Russian assaults were repelled.

On Tuesday, Ukraine's general staff reported troops had fallen back from areas in Lukyantsi and Vovchansk, which is a mere three miles from Russia, "in order to save the lives of our servicemen and avoid losses".

Ukraine war latest:
Putin's troops 'partially pushed back'

Almost 8,000 people were forced to flee last week when Russian forces launched their assault on Kharkiv, marking the most significant border incursion since the full-scale invasion began in February 2022.

In recent weeks, Moscow's forces have also sought to build on gains in the eastern Donetsk region.

Citing the escalation in Kharkiv, Mr Zelenskyy's press officer said on Wednesday all foreign trips were being cancelled.

Earlier today Ukraine's president cancelled plans for a trip to Spain and perhaps Portugal later this week but did not give a specific reason as to why.

Russia is opening new fronts in order to stretch Ukraine's army, which is short of ammunition and manpower, along the about 620-mile frontline, hoping defences will crumble.

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Russian artillery and sabotage raids have also been menacing Ukraine's northern Chernihiv and Sumy regions.

Mr Zelenskyy said in his nightly video address on Tuesday that the army has sent reinforcements to the Kharkiv and Donetsk regions.

"It is too early to draw conclusions, but the situation is under control," he said.

Antony Blinken, the US Secretary of State, who is on a two-day visit to Kyiv, sought to reassure its ally of continuing American support, announcing a $2bn arms deal - with most of the money coming from a package approved last month.