Russian President Vladimir Putin is expected to announce annexation of four Ukrainian regions on Friday despite international condemnation.

Putin is due to hold a ceremony at the Kremlin to declare Donetsk and Luhansk in Ukraine's east, and Kherson and Zaporizhzhia in the south as Russian territories.

He is also expected to sign what Moscow calls a treaty stipulating the regions' annexation in line with Russia's constitution.

The ceremony is to come after Putin signed decrees on Thursday recognizing Kherson and Zaporizhzhia as independent territories. He did the same for the two other regions, Donetsk and Luhansk, in February.

The moves are drawing international condemnation.

UN Secretary-General Antonio Guterres said on Thursday that any decision on the annexation "would have no legal value and deserves to be condemned."

US President Joe Biden said the United States will never recognize Russia's claims on Ukraine's sovereign territory.

The US and the European Union have announced plans to impose additional sanctions against Russia.

But a defiant Putin is pushing ahead with changing internationally recognized borders by force, just as he did for Crimea in southern Ukraine eight years ago.