LONDON - Britain, the United States, Japan and Canada will ban new imports of Russian gold as part of efforts to tighten the sanctions squeeze on Moscow for its invasion of Ukraine, the British government said on Sunday.

The ban will come into force shortly and apply to newly mined or refined gold, the government statement said ahead of a meeting of Group of Seven leaders in Germany on Sunday.

The move will not affect previously exported Russian-origin gold, it added.

Russian gold exports were worth 12.6 billion pounds ($15.45 billion) last year and wealthy Russians have recently been buying bullion to reduce the financial impact of Western sanctions, the government said.

"The measures we have announced today will directly hit Russian oligarchs and strike at the heart of Putin's war machine," Prime Minister Boris Johnson said in the statement.

"We need to starve the Putin regime of its funding. The UK and our allies are doing just that."

The latest initiative follows the London Bullion Market Association's (LBMA) March suspension of accreditation for six Russian precious metals refiners.

(Writing by William Schomberg, Editing by David Goodman)