German Chancellor Olaf Scholz will welcome leaders of the Group of Seven rich democracies to a three-day summit in the Bavarian Alps overshadowed by the war in Ukraine and its far-reaching consequences, from energy shortages to a food crisis.

The summit starting on Sunday takes place against a darker backdrop than last year when the British, Canadian, French, German, Italian, Japanese and US leaders met for the first time since before the COVID-19 pandemic and vowed to build back better.

Britain, the US, 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 the meeting. The move will not affect previously exported Russian-origin gold, it added.

Russian gold exports were worth 12.6 billion pounds ($A22.3 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.”

Soaring global energy and food prices have hit economic growth since Russia’s invasion of Ukraine, with the United Nations on Friday warning of an “unprecedented global hunger crisis”.

Climate change, an increasingly assertive China and the rise of authoritarianism are also set to be on the agenda.

The G7 leaders are expected to discuss options for tackling rising energy prices and replacing Russian oil and gas imports.

The summit takes place at the castle resort of Schloss Elmau at the foot of Germany’s highest mountain, the Zugspitze – the same venue as when the country last hosted the G7 annual meet-up in 2015. 

Then too, Russian aggression against Ukraine dominated the agenda a year after Moscow’s invasion of Crimea.

The summit is also a chance for Scholz to capitalise on being the host by displaying more assertive leadership on the Ukraine crisis.

The chancellor vowed a revolution in German foreign and defence policy after Russia’s invasion in February, promising to bolster the military with a 100 billion euro fund and send weapons to Ukraine.

But critics have since charged him with foot-dragging and sending mixed messages by warning that Russia might perceive NATO as a war party and highlighting the risk of nuclear war.

US President Joe Biden arrived in Munich on Saturday before continuing to Schloss Elmau. Along with the summit, he is also due to meet Scholz for bilateral talks.