Authorities in Russia-controlled Ukrainian territories say a large majority of residents in the areas have supported annexation plans by Russia in what they call "referendums."

Pro-Russian officials in two of the four occupied regions have asked Russian President Vladimir Putin to annex their territories.

The authorities, backed by Putin's administration, conducted the polls this month in the eastern regions of Donetsk and Luhansk, Zaporizhzhia in the southeast, and Kherson in the south.

The officials announced on Tuesday that a huge majority of the votes were in favor of joining Russia -- 99 percent in Donetsk and 98 percent in Luhansk.

The US think tank Institute for the Study of War said, "Russian officials pre-ordained and falsified the approval ratings and alleged voter participation rates for the sham referenda."

On Wednesday, senior pro-Russian officials in Luhansk and Kherson signed documents to ask Putin to incorporate their regions into Russia.

The chairperson of the lower house of the Russian parliament, Vyacheslav Volodin, said a plenary session will be held on October 3.

Valentina Matviyenko, who chairs the upper house, indicated that annexation legislation will be deliberated on October 4.

The Putin administration is expected to launch a procedure to unilaterally annex the occupied regions in Ukraine.

Ukrainian President Volodymyr Zelenskyy denounced the polls on Tuesday as a "farce," saying they could not even be called imitations of legitimate referendums.

Also on Tuesday, US Secretary of State Antony Blinken criticized the polls as a sham.

He warned that Washington will impose additional sanctions against Russia if it unilaterally annexes Ukrainian territory.