Britain imposed sanctions on a further 65 Russian companies and individuals on Thursday, including the Wagner Group, a private military force with ties to President Vladimir V. Putin, which has sent mercenaries into Ukraine.

Among the other targets are Polina Kovaleva, the glamorous stepdaughter of Russia’s foreign minister, Sergey V. Lavrov, and Galina Danilchenko, who was installed by Russian forces as a puppet mayor in the Ukrainian city of Melitopol. The Ukrainian foreign ministry said Russians had abducted the previous mayor, Ivan Fedorov.

Kovaleva, 26, who cultivated a high profile on social media, has become a vivid symbol of the privileged lifestyles of relatives of Putin’s associates. Protesters gathered in front of an apartment house in the affluent London borough of Kensington where she reportedly lives to demand she be placed on a blacklist.

The British government said Danilchenko, a former member of the Melitopol City Council who urged residents in a televised speech to adapt to the “new reality” of Russian occupation, was the first person it had placed under sanctions.

How the Wagner Group would be sanctioned was not immediately clear, given that it is a shadowy organisation.

Last month, European security officials said about 300 Wagner mercenaries with experience in Libya and Syria filtered into two separatist regions in eastern Ukraine to lay the groundwork for the Russian invasion; the statement referred to reports that it had also sent mercenaries to try to kill President Zelensky.