A new wave of infections from the Omicron variant of the coronavirus is moving toward the east of Europe, the World Health Organization (WHO) said on Tuesday, urging authorities to improve vaccination and other measures.

Over the past two weeks, cases of COVID-19 have more than doubled in Armenia, Azerbaijan, Belarus, Georgia, Russia and Ukraine, WHO's Europe regional director Hans Kluge said in a statement.

The comments come at a time when several European countries including the Czech Republic and Poland have hinted at easing of COVID-19 restrictions next month if daily infection numbers kept falling.

The WHO, however, stressed the continued need for measures such as rapid testing and masking, saying over 165 million COVID-19 cases have been recorded so far across the WHO European region, with 25,000 deaths in the past week.

"Faced with the Omicron tidal wave, and with Delta still circulating widely in the east, this worrying situation is not the moment to lift measures that we know work in reducing the spread of COVID-19," Kluge said.

He also called on governments to examine local reasons for low vaccination rates. Less than 40 percent of those aged over 60 in Bosnia and Herzegovina, Bulgaria, Kyrgyzstan, Ukraine and Uzbekistan have completed their COVID-19 vaccine series, he said.