Residents of four areas of Ukraine controlled by pro-Moscow forces have started voting in the so-called referendums on joining Russia, polls widely condemned by the west as illegitimate and a precursor to illegal annexation, writes The Guardian.

Voting in the Luhansk, Donetsk, Kherson and Zaporizhzhia provinces, representing about 15% of Ukrainian territory, began on Friday morning.

Russian-installed leaders announced on Tuesday plans for the votes, a challenge to the west that could sharply escalate the war. The results are seen as a foregone conclusion in favour of annexation, and Ukraine and its allies have already made clear they will not recognize the results.

Kyiv this month launched a counteroffensive that has recaptured large swathes of territory, seven months after Vladimir Putin ordered the invasion of Ukraine, starting a war that has killed thousands, displaced millions and damaged the global economy.