KANANASKIS, Alberta (Reuters) -Britain announced new sanctions on people and groups it said were linked to Russian finance, energy and military operations on Tuesday, including two UK residents it accused of sending high-end electronics to Moscow for the war in Ukraine.

The two - a Ukrainian and a Polish national living in Britain - had operated "a shadowy network of shell companies" to funnel more than $120 million of technology to Russia, Prime Minister Keir Starmer's office said.

Six entities had been added to the sanctions list, it added, as well as 20 ships from Russia's so-called "shadow fleet" - vessels that Western powers say are being used to help Russia evade price caps and other limits on its crude oil.

Britain imposed sanctions on two companies it accused of crewing and managing the vessels. The penalties would also target the Russian GUGI military agency responsible for underwater intelligence, a move that would protect Britain's subsea infrastructure from attack, Starmer's office added.

“These sanctions strike right at the heart of Putin’s war machine, choking off his ability to continue his barbaric war in Ukraine," Starmer said in a statement.

Russia's embassy in London did not immediately respond to a request for comment. Russia has previously called Western sanctions illegal and said they destabilise global energy markets.

Starmer is expected to talk about the sanctions later on Tuesday at the G7 summit in Canada.

He will say he wants "to work with all of our G7 partners to squeeze Russia's energy revenues and reduce the funds they are able to pour into their illegal war," according to advance excerpts of his remarks released by his office.

Britain has already imposed sanctions on more than 2,300 individuals, entities and ships since Russia's 2022 invasion of Ukraine.

Starmer's office said the electronics sent to Russia included many Common High Priority items - advanced components including microelectronics deemed by the U.S. and European Union as likely to be used for Russia's war in Ukraine.

The two people named in the British statement could not immediately be reached for comment.

(Reporting by Suzanne Plunkett; Writing by Sachin Ravikumar and Sam Tabahriti; additional reporting by Muvija M; editing by Sarah Young, William James and Andrew Heavens)