Moscow - The upper house of Russia's parliament voted on Tuesday to approve the incorporation of four Ukrainian regions into Russia, as Moscow sets about formally annexing territory it sized from Kyiv during its seven-month conflict.

In a session on Tuesday, the Federation Council unanimously ratified legislation to annex the Donetsk, Luhansk, Kherson and Zaporizhzhia regions of Ukraine, following a similar vote in the State Duma, Russia's lower house, yesterday.

The documents now pass back to the Kremlin for President Vladimir Putin's final signature to complete the process of formally annexing the four regions, representing around 18% of Ukraine's internationally-recognised territory.

Russia declared the annexations after holding what it called referendums in occupied areas of Ukraine. Western governments and Kyiv said the votes breached international law and were coercive and non-representative.

(Reporting by Reuters; editing by Guy Faulconbridge)