NATO Secretary General Jens Stoltenberg has said the coming days in Ukraine are likely to be worse as the Russian Armed Forces introduce heavier weaponry and continue their attacks across the country.

"The coming days are likely to be worse, with more deaths, more suffering and more destruction, as the Russian Armed Forces introduce heavier weaponry and continue their attacks across the country," Stoltenberg said at a press conference following the meeting of foreign ministers of NATO countries in Brussels on Friday.