Zelesnky will not give away the south to anyone

President Volodymyr Zelensky vows Sunday that his forces "will not give away the south to anyone" after his first visit to the southern frontline.

Making a rare trip outside Kyiv, where he is based for security reasons, Zelensky travels to the hold-out Black Sea city of Mykolaiv and visits troops nearby and in the neighbouring Odessa region for the first time since the Russian invasion.

"We will not give away the south to anyone, we will return everything that's ours and the sea will be Ukrainian and safe," he says in a video posted on Telegram as he makes his way back to Kyiv.

The war in Ukraine could last "for years", NATO chief Jens Stoltenberg warns in an interview published Sunday by German newspaper Bild, while reiterating calls for Western countries to provide long-term support to Kyiv. 

"We must not weaken our support of Ukraine, even if the costs are high -- not only in terms of military support but also because of rising energy and food prices." 

Ukrainian troops have repulsed Russian attacks on villages near the eastern city of Severodonetsk, where the two armies have fought bloody battles for weeks, Kyiv's armed forces say Sunday.

"Our units repulsed the assault in the area of Toshkivka," the Ukrainian army says on Facebook. "The enemy has retreated and is regrouping."

A day earlier, officials said fierce battles were taking place in settlements outside Severodonetsk, which they say is mostly, but not entirely, under Russian control.