Britain said it was introducing new sanctions against Russia in response to "illegal" annexation referendums held in four Ukrainian regions under full or partial control of Moscow.

"The sanctions we are introducing today target all those behind such election farces and individuals who continue to support the war launched by the Russian government," British Foreign Minister James Cleverley said in a statement.

Among the 92 legal entities targeted for sanctions are "Russian high officials who organized the illegal referendums in four Ukrainian regions and Putin's favorite public relations agency," the announcement reads.

It is about 33 people sent to the areas where referendums are held by the agency IMA Consulting, which "organized public campaigns for these referendum farces", especially to "defend their false legitimacy in Russia", the Ministry adds.

Four oligarchs have been added to the list of people under British sanctions.

Britain has so far imposed sanctions on more than 1.200 people and 120 companies and organizations in response to Russia's invasion of Ukraine in late February.